system
Given the following post, respond as if you're commenting on Reddit:
human
[Marvel What If...?] How did Ultron...?

...defeat Thanos so easily with just one infinity stone, while Vision from the "normal" MCU universe couldn't do it?
gpt
Ultron got lucky. There are probably countless timelines where he doesn't, and Thanos kills him. But we weren't watching those timelines. The question in the episode's title was "What If Ultron Won?", not "What If Ultron Won And Then Lost Later?"

Ultron only has to get lucky in one universe to become a threat to all of them.