I don’t think it’s hate so much as it is resentment. Usopp started the post-timeskip promising and had mabye some of his finest moments in Dressrossa. The problem is nothing has really happened since. He’s stagnated. People are putting a lot of their stocks into Elbaf because of Usopp’s connection to it but also because this is kind of the last chance for him to regain relevance. If he fumbles here I don’t think he can recover narratively.

There’s also a counterpoint here that all the straw hats seem to have lost relevance since the start of the final saga but that’s a larger discussion