Not super enthusiastic about his chances (or him in particular) he's got baggage like the mess that was stop and frisk from his time as NYC mayor (similar justice issues aren't helping Kamala Harris), is occupying a lane similar to Joe Biden (moderate and 'electable' with a less high profile former position), and is a New York finance (kinda) billionaire (which wins you few friends on the more liberal side of the party, plus there's already another billionaire in the race trying the same kind of thing).
Might be good insurance policy to spend $50 million or more and fail to become president - and damage the prospects of anyone from the progressive wing of the Democratic party while doing so- than having Warren or Sanders become president and take a real haircut in taxes.
That's bad for dems. "Stop and frisk" Mike Bloomberg isn't even liked by New Yorkers let alone everyone else. This means he thinks that the dem field is so weak, he considers himself an _improvement_. I disagree. I think this only weakens the already weak roster of candidates.