This is a question I get often. From people online, from my friends, or from my brothers with whom I play less frequently than I'd like. Often, the question is prompted by a game that has everyone excited, but won't have a Linux version, or simply doesn't run at all, even with Wine / Proton.
And I didn't really think about why before now. An annoyed shrug was my answer, wondering "yeah, why don't I just double-boot and play on Windows ?". Well, I have an answer now !
I hate double booting
Double booting sucks. You have to stop everything you're doing, restart your computer, select your second OS (impossible to do with a bluetooth keyboard, so that also means I'd have to use a wired keyboard and clutter my perfect desk), wait for it to boot, and restart the various launchers / Discord / whatever you use to play.
There is also the jarring transition of using an OS I'm deeply familiar with, and moving to Windows, an OS I haven't used as a primary system for a long time now.
Double booting is also very space inefficient: you have at least 20-30 Gb lost just to run that second OS. It also demands some organization to not turn into a nightmare: put all your games on one of the OSes, or you'll spend your time moving back and forth, rebooting your machine, or end up with games you installed on both systems (extremely inefficient).
There's also the update situation. Everything gets updated nowadays, and on a secondary system, you'll get pestered everytime you boot into it to update the OS, the games, the launchers, the applications you use. It's a huge loss of time, especially since Windows likes to reboot after updates, and its updates can also break GRUB from time to time.
You'll also find that, somehow, you still need some of your files on both systems, so you don't have to reboot that often. In the end, double-booting Windows asks for too much mental control to avoid moving to Windows completely, since it ends up having all your stuff after some time.
I like to tinker
That's just me, but I like that I have to tinker to get a game working. It takes some time, some research and a bit of inventivity to figure out why your game doesn't start, or doesn't play videos, or has poor performance. I find the whole process very rewarding, when you finally manage to get the game running, even if you just followed a guide on the internet.
I get that it's not for everyone. People generally just want to click once and enjoy their game, but I really enjoy the process of deep diving into the game's files and options, and configuring whatever needs to be done in Wine or Proton.
I grew up with Linux as my main OS, and in these days, everything was a battle to get up and running, or simply maintain in a functional state. I learned a great deal about computers, drivers, software, and the innards of Linux as a result, and I really enjoy this side of computing.
I love the miracle of Wine / Proton
If you think about it, Wine and Proton are little miracles. I mean, really, think about it. These magnificent pieces of software don't just emulate Windows, they actually implement Windows' DLLs, APIs and system features in a new way, that translates these calls to the equivalent Linux instructions. Its basically a translation layer for two systems that don't speak the same language at all.
The fact that a lot of games (about two thirds of all games listed on ProtonDB run with Gold or Platinum status, meaning they're a one click install and work about as well as they do on Windows) just work on a system they were never designed to run on is nothing short of amazing.
Everytime I play something through Proton or Wine, I'm blown away by what my computer is doing. Sure, not everything is perfect. Some games have lower performance than on Windows, some don't even run at all, and some are so close to run it's frustrating to see that they are held back by DRMs or anti-cheat software.
But, in the end, no other system has achieved that kind of technical prowess.
I want to support Linux and developers who make games for it
I talked a lot about Proton and Wine, but a lot of games are also getting a native Linux version nowadays. It's far from the majority, and there are still a bunch of issues, the most frequent one being that Linux users are served a few months / years after their fellow gamers using Windows, but still, Linux is on the radar for a bunch of developers.
I love Linux, I want it to expand its reach on the desktop, and gaming has been a major roadblock. The more developers support Linux natively, the more people will take a look, or even a shot, at running it.
So when a game I want to play has a Linux version, I'd rather wait for it to release than just buy the Windows version and play it on Microsoft's system. In the end, maybe that support will also translate into other types of software, mainly productivity applications.
Going back to Proton and Wine, Steam also now classifies people playing with Proton as Linux users, so developers can actually see how much time people spent playing on that system, even though the game doesn't have a native Linux release. This might, at some point, make them think about developing a native Linux client for their next game: if they see enough of a potential market, why not support it for their next project?
It allows me to be more selective and better spend my time
I don't have as much free time as I would like. I have a regular day job, I have my YouTube channel, I have a personal life with friends, family, a significant other, and as such, I simply can't play as much as I used to. I actually sold my Xbox One X and PS4 + PSVR for that exact reason: I never played them anymore, electing to play games with my friends, who are all on PC.
Gaming on Linux, while not as restrictive as it used to be, still reduces my choices. I can't play Fortnite (not that I would want to), Apex Legends, or some other game that would gobble up all your free time. Since my gaming time is limited, I have to think about what game I'd really want to play, and select those games from a more restricted library than what Windows gamers enjoy.
So, in the end, I spend less time playing stuff that I kinda like but I won't remember when I'm done, and more time playing stuff that I really enjoy. I can also be frustrated by some missing games. I really want to play Vermintide 2, but I can't. I'd love to continue my journey into Gears of War, but Gears 5 doesn't run on Linux. I will probably want to replay all Halo games, but the PC version of the MCC will probably have the same issue as Gears does (namely, Easy Anti Cheat).
I still feel it's a net positive. Since I have to look at every game and check if it runs on Linux or not, and how well it does, it also enables me to think more about it, and to pick the games I'm really hyped for.
I don't want to use Windows
That's personal, but I really don't like Windows. 98 was the ugliest thing I had ever seen, XP broke compatibility and looked like a kid's toy box, Vista ran terribly slowly on anything but high end computers, 7 was ok but still bloated, 8 was a bad joke on desktops and laptops, and Windows 10 is basically spyware with a bow tie.
This OS is inconsistent, slow, disk space hungry, and absolutely insecure. It bugs you for data, for updates, and is impossible to really tweak to your liking. I don't like Windows, and I don't want to run it on my machine. Microsoft makes some good stuff. Office 365 is great value. OneDrive is a good cloud service, Teams looks pretty neat, I loved the Xbox and what Microsoft was doing to catch up in the "console war". I think Xcloud will be great, and Game Pass is amazing if you don't mind renting games.
But Windows ? Windows is a relic, and I have a few thoughts on the matter, that I'll share with you soon. And relics don't have their place on my shiny desktop !
Phew. That cleared my mind. Now, the next time someone asks me why I don't just dual boot, I'll simply answer: "No, thanks" with a knowing smile, and feel inside of me that I do have reasons for not going back.