What was the point of Thanos de*spoiler*
Destroying the infinity stones?
I'm not what you'd call a mcu fanatic but I have seen most of these films, although only once, so maybe I'm not remembering something but...
Why did he bother going to all the trouble of getting them (and exciting everyone by turning up in those mid / post credit scenes) just to snap the world's population back to 1970s levels and then just give up? Wasn't he supposed to be some ancient creature who'd be wanting to do this for a long, long time?
What was the point if all his efforts would be undone after another 30/40 years? (like I say I'm not the biggest fan so maybe they covered this but I just missed it...)