The Death of Thanos

This is pure speculation,, of course, which, for now, is still possible in the world.

Why, I ask, did Thanos (one of the greatest villains in cinematic history), turn into such a loser in the MCU movie, "Endgame"? What happened to the amazingly believable and amazingly horrifying Thanos from the preceding MCU movie, "Infinity War'? Why did Thanos have to be killed twice? This is a theory.

What do you think?

Infinity War: https://www.imdb.com/title/tt4154756/
Endgame: https://www.imdb.com/title/tt4154796/

(and if there is a copyright knock on this video I will post a second with nothing but my ugly mug talking)