Actually, you're both partially wrong. MCU Thanos' motivation is not radically dissimilar to the one in the comics. It is just that a lot of people have forgotten what his motivation actually was in the comics.
Minor spoiler:
This got me rereading Infinity Gauntlet. Because it didn't match up with the love stricken doof I remembered. I present Thanos' self-proclaimed cosmic purpose, spoken to Death about why he collected the Infinity Gems:
"But I only sought such glory to become worthy of your love. Your heart deserves better than the thrall I was."
This is in amongst some hilarious why-won't-you-notice-me-sempai type dialogue as Thanos begs, pleads, threatens, blows up a minion, and otherwise tries to get Death to love him. What a maroon.