Not often, but it does happen.
I bought several PS3 games (Black Friday deals) before getting my PS3. I had every intention of getting the console though.
My bother bought me "The Thing" for Xbox in 2001 or so as a gift. I found an Xbox a few years ago for 20 bucks, so it was probably 15 years before I got the console. Still in my backlog...in hindsight I should have kept it sealed, lol
I currently have 8 PS5 games, despite not owning a PS5. All sealed. Still undecided on the PS5. They are in stock now but I don't see any reason to drop 600 bucks after tax on one...nothing screams "play me!". Hoping for a cheaper "slim" model in a year or two.
I have 24 Wii games, but no Wii. I do have a Wii U and the accessories needed to play them all though.
I have 7 PS2 games, though I've never owned, or plan to own, a PS2. 4 are sealed.
Edit:
I have 3 switch games, all sealed. No plan to get a switch, but I may someday (I hate the joycons though).
I have 1 PSP and 4 vita games, all sealed. Don't own either system, but wouldn't mind owning them.
So I don't go out of my way, but if I see a great deal I'll pick up something for a console I don't own.