What are you talking about? He lost the Democratic nomination to Mamdani. Now he has to run as an independent.

https://en.m.wikipedia.org/wiki/Spoiler_effect

He knows exactly what he's doing

Primaries are held by parties. It’s not entrance into the general election. Anyone with the cash can run as any party they choose.

Yep, and a losing candidate can choose to participate in the general to ensure the opposing party wins by splitting the vote, which is what the establishment Dems do when a progressive successfully primaries the..