Here's the thing: all the games you buy for that console will also be playable on that PC, as long as they're not console-exclusive, so if you buy PC today, and 7 years from now a new game will be released on both XBox One and PC, you'll be able to play in it on your PC. The 3-4 year mark is for the PC-exclusive games.
Funnily enough, on PC, you'll also be able to play in previous generation console games (provided they've also been released on PC), and even in some next generation games that will be released on XBox Two or PlayStation 5. You will also have better video quality on PC for some games, you'll get a solid workstation useful for more activities than just gaming, and any additional cost you'll bear buying the PC will be recovered on the games prices.