MotoGP has some of the tightest, best racing around. You've got 300 horsepower monsters being straddled and sent flying by true superhumans each weekend all around the world. Wheelies are had, crashes are mind-meltingly insane, and they sound bananas flying down any track straight. Championship fights are close all the way down to the final race, something that's not always the case with top-tier series.
Yet, despite all that, MotoGP holds a fraction of the viewership of Formula 1.
Part of that is, obviously, fewer people ride motorcycles versus drive cars. But Formula 1 cars aren't actually cars. They're rocket ships. They have about as much to do with your on-road Mercedes or McLaren as I have with Tony Stark. So while the audience is more niche comparatively, I don't think that has as much to do with MotoGP's smaller fandom than people may think.