The Way Forward

specifics of "who" as much as "what." Just a suggestion.

You'd be surprised what wikipedia and Google can help you find... only four out of 25 billionaires (20% of a short list) but every name matters, right? This is a start, but other lists are findable.
https://en.wikipedia.org/w/index.php?search=Democratic+Donors&title=Special%3ASearch&ns0=1
https://www.opensecrets.org/outside-spending/top_donors

8 Bloomberg, Michael R.
City of New York, NY
New York $46,076,784 $1,000,000 $42,576,784 2.3% 97.7%

13 Hoffman, Reid Garrett
LinkedIn Corp
San Francisco $30,135,600 $400,000 $23,495,600 1.7% 98.3%

14 Simons, James H. & Marilyn
Renaissance Technologies/Simons Fdtn
New York $29,400,000 $0 $29,400,000 0.0% 100.0%

17 Eychaner, Fred
Newsweb Corp
Chicago $28,445,000 $0 $28,445,000 0.0% 100.0%

22 Mandel, Stephen Frank Jr. & Susan Z.
Lone Pine Capital
Greenwich $22,635,000 $50,000 $19,085,000 0.3% 99.7%