My friend, I'm well aware of modern political history within the Democratic party. That doesn't change the fact that your heuristic is not a good one; there are plenty of reasons to run a second presidential campaign besides fundraising, even if you don't think you're likely to win (and Biden had to know he wasn't in '08).

Moreover, Bernie's campaign strategy in '16 was poor, and his run in 2020 amended that by focusing a lot more resources into Iowa early on. Unfortunately, Buttigieg played the same angle and the caucuses were a total debacle besides, which robbed the campaign of the momentum it had hoped to generate with a big win in Iowa (which, you'll note, is exactly how Obama won in 2008.)

Edit: I'd be a lot more inclined to listen to your request for respect if it didn't follow an incredibly condescending comment. Also, I'm well aware of the uselessness of electoral politics--but it was 2020 that cemented that for me, and for many others as well, particularly here. So even in that sense, Bernie's 2020 run had real impact.