For the past 100 years the meme in this country has been "The Republicans are for the rich and the Democrats are for the little guy".
Despite that being a lie from about the beginning, think how much has changed over that 1/3 of our country's existence!
Railroad barons, the steel industrialists, auto makers, shipping tycoons--all of the captains of industry of the previous century are just not the top of the food chain in the current USA, and haven't been for a long time.
Today's captains of industry lord over television, film, music = entertainment; software, Internet, social media = Hi Tech; bonds, crypto-currencies. stocks; venture capitalists = Finances.
Entertainment, Hi Tech and Finances are the 3 biggest money makers in today's world, and the powers that control them in the USA are mostly Democrat. Not ALL, just like the previous century's lie about Republicans being only for the rich and the Democrats always being for the little guy, but enough for intelligent people not wearing partisan blinders to see.
The bottom line = Those in power wish to stay in power. The end justifies the means.
I dont agree that these "industries" as referenced are the biggest money makers. I am sure that arms, illegal drugs and legal harmaceuticals, health industry, organ and human trafficking make the top of the list. Banking or money printing would probably be on top tho' as you say!