Wrong: "Nobody likes him."
Bernie Sanders beat Hillary Clinton in 23 of 57 Democratic presidential primaries, knocking down 43.1% of the total national Democratic primary vote, in 2016. Apparently some people like him.
Right: "He was a career politician."
He's spent the last 38 years in, or briefly out of while running for, political office -- the last 28 of them in Congress. So yeah, he's the very definition of a career politician.