If you want to know why wealthy leadership supports Biden, just look at a health insurance stock on the news of the Klobuchar endorsement.
These people give the DNC and members a lot of money. They provide lobbying jobs for them later in life. There is a lot of money at stake for people involved in the party.
Biden is also very good for the pharmaceutical industry (and bad for you if you want to get a vaccine at a reasonable price).
https://theintercept.com/2020/03/02/...ouging-senate/