I've heard two potential strategies.
1. He wants to be on the ballot in later states in case the centrists fall. So if the nomination is a fight between Warren and Sanders after Biden and Buttigieg collapse, Bloomberg can run as the moderate alternative.
2. He's hoping for a brokered convention. He has a media empire that could blanket the airwaves for months to create momentum for his campaign. He could easily spent a billion dollars on consultants, organizers, and activists. He could even afford to pay every delegate a million dollars and it would be a little under ten percent of his net worth.