I'm honestly in the same boat. The convergence of the Apple OS ecosystem makes the Mac Mini a serious option though, something that a custom gaming PC won't be able to truly offer, unless you can figure out a way to install Big Sur on an Intel chip gaming PC. Even then, there's a reason why Apple is moving to SoC. It's a question of efficiency.
Yes, you can install more RAM on a gaming PC, but the M1 can do more computations with less RAM, so, it's a different ballgame altogether. I personally bought my last (and first) Apple computer almost 10 years ago now, and it's still performing rather robustly. Granted I've been able to add RAM to it, and add a secondary SSD.
I think taking a bet with the Mac Mini is a very viable option, especially given the security and privacy concerns that come with Windows OS. There's no other really serious contender in the OS sphere, unless you're a pro Linux/Python coder that can build yourself a system as secure as MacOS. But that's kind of what you're paying for when you get the Mac Mini. It's all the developer ecosystem, future updates, and responses to future security threats.
That's why I'm leaning towards Mac Mini, even though it would be nice to have a powerful gaming PC that I can upgrade every year, and perhaps mine crypto when I sleep. And yeah, maybe you will have to get a new Mac Mini in 5 years time, given how fast technology moves, but imagine being one of the few who has a Mac Mini in 2021. It'd be like being one of the few who had the first iPhone when it came out in 07/08. Automatically at an advantage. Also, this will give an incentive to game developers to include AppleTV OS as a platform for future games. Surely most won't, but some will, and it will be worth the ride.