Single-player PlayStation will usually not arrive day one on PC, so there is a downside to waiting. Naturally, if what you care about is just playing games as fast as possible, then you should definitely go ahead and
buy a PlayStation 5. If you already have a gaming PC and you're okay
waiting a year or two for games to be ported, you really don't have to buy a PlayStation 5!
In general,
this approach allows you to save money, as you often won't be paying full price for a game, and it will usually include all of the DLC or expansions, as is the case with Horizon Zero Dawn Complete Edition and Marvel's Spider-Man Remastered.