Well, he said his campaign would be self-funding....
So maybe he is funding himself, if you get my drift.
How much did the rent on his office space go up?
Yes Trump proclaimed loudly and early that he couldn't be bought, and donors need not support him and by extension the GOP. Why would anybody give money to a multi-billionaire?
Then he picked a fight with and bad mouthed every Republican he could.
Why would people donate to those "losers?"
Then he picked the most divisive issue possible (immigration) as the center of his campaign and waffled on every core Republican principle until his loudest supporters were the alt-right.
Then he picked the most anti establishment campaign manager he could find (Bannon) and gave him access to the GOPs donor rolls and fundraising tactics.
Checkmate!