Buy your games on GOG and own them forever. You can also buy a cheap, slow as hell external drive and backup your installer files, too. You can still buy games on Steam since most of them don’t have DRM. For now, Steam is also great, but a decade from now they could enshittify.
If you only do console gaming, buy physical cartridges and discs as much as possible. You’ll keep most of the game and can play whenever you want. An example of being able to play “most” of the game applies to games with legacy activation servers, such as Splinter Cell Blacklist and Watch Dogs 1. Most of the game is playable, but anything that requires a connection to that activation servers no longer works.
Finally, scour Craigslist, flea markets, and yard sales to buy old game consoles from before this DRM mess. All those old games still work great. If you buy Wii U, 3DS, and Switch 1, make sure to boot your console and every single game at least once every few years. Yes, every single one of your games. Due to NAND volatility, this will protect your games and console (Wii U) from NAND failure and increase longevity.
Edit: removed Nintendo DS from the list I provided. Nintendo DS does not use NAND; rather, the DS uses mask ROMs which does not have the limitation of NAND volatility.
