

It started as only a few (chiefly the Murdochs via constant free publicity via Fox News, though they disliked him personally). Rank and file Republicans, and lots of formerly disengaged people just kept voting for him, and consequently he kept winning primaries. Even the Koch brothers kept staking challengers against Trump (notably and most recently Desantis). Over time, cowardly billionaires joined the bandwagon – they’re firmly in his pocket now, but it’s worth remembering that’s not how he started.
How odd, could have sworn I’d put the link in. Edited to add.