Thanos used his standing as the Avatar of Death to quite literally bring Death to an entire reality, bringing an end to the Many-Angled Ones' crusade across the multiverse, saving all of Earth-616 ...

Thanos expects him to pay Thanos back with interest if he wins instead. Of course no one quite understands that this is a last man standing type of game, but we'll let that slide. Despite Thaqnos ...