Steyer is too obnoxious, toxic and too poor(at a net worth of only $1.6 Billion, he simply isn't rich enough for his money to make much of any difference in a presidential campaign).
Bloomberg is entirely another matter altogether. With a net worth of a staggering $52 Billion, and a known willingness to spend unfettered amounts on his campaigns, he can literally buy his way into being a top contender in literally any race he wants.
This is a guy that could spend $10 Billion on a presidential campaign if he wanted, without batting an eyelid.
Read this:
Cost of Being Mayor? $650 Million, if He’s Rich
https://www.nytimes.com/2013/12/30/nyregion/cost-of-being-mayor-650-million-if-hes-rich.html?hp