The Bernie copycats now realize that they're not going to get his voters. They're moving on to pastures where they think they can get votes. It's never about policies or convictions for them. Just a game to get elected.
This is actually where Bernie differs from others. The theory that politicians will move to a centrist position in general elections. For most of them it's more about pandering than personal and ideological convictions.
Bernie never had to do this ideology change of general vs primary because he never competed in primaries before 2016. He always ran for the position representing everyone than his party electorate. So him moving towards center is not going to happen in general.
