so basically, you buying an expensive GPU just to run a few games that you probably wont play
Yes but most PC need a GPU to show a picture.
While some CPU have igpu in them now, they aren't really capable of running a game (besides laptops which well, some can)
but the igpu inside desktop CPU aren't at that level yet,
So most people still need to buy something to play games.
Whether they need the top end is questionable.
And you never know, there might be a AAA game worth buying one day. So having a GPU that can run it is handy... just not worth having one that costs a fortune and randomly causes fires
There can be other reasons to get a new card, you might have a monitor with a refresh rate your current card can't match, so quality of life improvements can be a reason. I had a 2070 Super that could only run my screen at 100, but screens max is 144. Now my GPU can run faster than my screen which is a better position to be in. I am thinking about a new monitor next year but might try to stay within range GPU can run 2k at.
New cards can make old games run better... unless its a 50 series card and game uses physx (Black Flag for instance).
Generally replaying old games on new GPU is a better experience.