It allows self-hating nerds to empathize with themselves a little bit, but doesn't force them to confront anything about their self image too directly. Rick is basically the embodiment of how some people deal with rejection. They lean into their 'intelligence' and come to believe that their nihilism, loneliness, and antisocial behavior are just a product of everyone else being stupid. Most people are self aware enough to reject this self-image, but still partially accept it at a subconscious level. This causes some self-hatred because they know it's bad to be like that, but also they kind of want to be. The show does the same thing by criticizing Rick explicitly but validating him at the level of subtext. The show is a portrayal of an angry loser's self image, but it's more humane and empathetic about it than, say, South Park, which just tells people that it's good to be an asshole who doesn't care about anything.

Also, probably a lot of people just think it's funny.