I thought he was doing the financing of the gun-grabbing group. Maybe I'm mistaken, but since he has more money than he can spend, that makes sense. Anyway, since he has more than he can spend, he has decided to throw a big chunk of it away in a race against Trump. After the Nevada debate, he will be forced to double down on the spending to try to reverse the damage before Super Tuesday. At least he is providing employment for thousands of people in an attempt to show billionaires are good for employment numbers.
It takes a huge ego to run for POTUS. It takes a huge ego and a winning message to be nominated POTUS. What is Bloomberg's message? Not Sanders? Not Biden? Not going to do the things you fear the most (unless elected)?
Democrats are frantic to find a nominee that has a chance to beat Trump. If they are truly desperate, they will accept whoever comes up with the most believable con job. Siince Bloomberg used to pretend to be a Republican, he has shown his ability to pull the wool over the eyes of a lot of voters. That may mean a lot to some Democrats.
A battle of the billionaires might be interesting. It would certainly result in a transfer of wealth to the pockets of campaign workers. But an election does that anyway, so a race with these two would just be a spectacle of a different sort. I think the outcome is already decided, just as the whole "impeachment" drama was decided before the first posturing political hack took center stage in the House of Representatives to prance and preen for his or her admiring audience of psycho-phants (sycophants in reverse or something, I guess -- I just liked the sound of it).