Trump and Bloomberg are running in completely different primaries. While the GOP base might find a billionaire palpable the Democratic base is not so friendly to big business or wall street. There is no uniting force in the Dem party like the Evangelical vote. That veibn said I still I donated another $27 dollars to Bernie.
Which is exactly what most people thought about Trump's candidacy.
These days all kinds of stupid things happen. If you oppose Bloomberg (or any other candidate) you shouldn't sit back and just wait for his campaign to implode.