Musk has a particularly obnoxious fanbase[1], it contribute to the hate Musk gets from outside this fanbase. Zuck has no real fanbase to speak of.

Musk is more politically active than Zuck, especially recently. Politics cause hate.

Musk is loud and provocative, sometimes insulting for no good reason, and has an opinion on everything. Zuck is a bit of that too, but Musk is much more.

So general idea is that out of the two, Musk is seen as the bigger asshole. A productive asshole, maybe, but no matter how productive they are, people usually don't like seeing assholes.

[1] https://medium.com/@mspies28/worst-dedicated-fan-base-tourna...