The debates made it clear: Bloomberg joined so the Establishment Dems can look good.
They all got to attack him. He was the easy target. He diverted them from attacking each other - except Bernie. And that's the point isn't it? If not for Bloomberg, they'd have been either attacking Bernie or each other. And they don't want to attack each other at this stage any more than necessary because it will take all four of them - Warren, Biden, Buttigieg and Klobacher - to divide up the vote and allow the DNC to invoke the super delegates to steal the election from Bernie.
Especially with Biden probably falling by the wayside long before the finish line.
But most of all, Bloomberg allows the others to appear less to the right.
A GOP candidate is basically what Bloomberg is. He's not conceivably electable. But by running, he allows the others to appear reasonable. Then everyone forgets the centrists are still corporate owned and not one bit better. At least, that's their hope.
It isn't going to work though. Bernie just keeps skyrocketing. They're going to have to steal it.