And if you're new enough to the space to be building a first computer for $400, odds are you don't own the best games of the last 20 years, the vast majority of which will be regularly available for less than ten bucks, and will run well above low settings on that modern budget rig. Todays budget used hardware was high end four years ago, and beyond the market entirely eight years ago. And with the relative plateau that graphics have seen, those games from eight years ago look nearly as good as what you're getting today anyway.
Same applies if you're old blood in the space who just runs on budget hardware, your old games aren't suddenly ass. Even linear single player titles will feel fresh after being left to lay fallow for a year or two. Like watching an old favorite tv series or reading an old book set, its still good once the details have had time to fade. If anything, games handle returning to them after a few years even more gracefully, as fun gameplay can carry an otherwise exhausted story - Ace Combat 7's narrative doesn't really matter much when the gameplays as fun as it is, and its why I return to it and Project Wingman pretty regularly every year now. They're just the right kind of fun to fill out a month, replaying over the old stuff and relearning the ropes without getting burned out.