I wouldn't say paranoid - election fraud has been a Democrat staple for sixty years, now. But he knew that going in, or should have - and what he should have been doing is uniting the party, not b!tch-slapping conservatives and their most-popular candidate.
He's not going to make any progress fighting this risk, in trying to out-Bernie Bernie. A few Sanders kooks might come and vote for them. The Democrat Machine, however, will not be amused - and will see Trump as even more of a risk.
To the Democrat Machine, it's not positions - or even popularity. It's keeping their flabby fat @sses in the middle of the money stream. And THAT can only happen when they WIN.
By fair means or foul. Ergo, cemeteries rise up en masse to vote on a certain Tuesday night.
And if Trump is just now discovering this reality, then he's a bigger j@ck@ss than I thought, even.