FWIW, we'll continue to monitor future developments about this key aspect of Trump's "outsider' candidacy.
Here are two recent news articles however, which call the 'self-funding' image into serious question.
↓..Just don't call him 'self-funded'. Or an "outsider".....↓
(Off-site links, new windows open, no affiliation)
(YT video link. No ownership claimed. No affiliation. ↑Some coarse language, gestures, indications... de rigueur..)
(YT video link. No ownership/affiliation)