Honestly, I'm sure Elon does really want the WI Supreme Court (SCOWI?) to rule in Tesla's favor on the question of whether his car dealerships in the state need to be franchised, but I don't think that was really the main issue for him in this election.
More than anything, I think he wanted to establish himself as the go-to guy for funding for the entire GOP. A win would have created the impression that, in a moment of intense backlash against Trump, his money was what Republicans needed to win elections, and so he would get to pick who gets the sauce and who doesn't. He's already got a lot of power in that party, but this would have forced any grumblers to just stfu and eat whatever shit sandwich he wants them to eat.
I think this was a power move bigger than just a relatively minor (for him) matter of whether or not Tesla needs to be franchised in Wisconsin. McDonald's is also a franchise, so are most gas stations, so is 7-11, and McDonald's, Exxon, and 7-11 are not exactly unprofitable companies. It's an issue for him, but not something to bet the farm on. (Admittedly, he's not a rational person, and he seems to just get obsessive over dumb shit, so maybe I'm completely wrong about this, but ultimately I just think he was aiming higher than that.)