I dunno, I think this is just a case of viewers buying into the nonsense Thanos is spouting in the first one, then getting disappointed when he shows his true colours in Endgame. His rhetoric does not change at all, just his attitude when he realizes he was wrong. In IW he gets to make all these calm, prophetic declarations cause he's so sure he's right. Then we see broke farmer Thanos is depressed because it didn't work, he spitefully destroys the Stones because he's tempted to reverse it. Then Younger Thanos is high on his own supply after witnessing his future death, and starts gleefully talking about destroying the whole universe and making a new one, because the guy can not handle being wrong.