Presumably, the cash injection at the start of a million or so dollars didn't hurt Trump's chances either -- and has he really been all that successful? One argument I've seen was that, allowing for inflation, Trump could have done literally nothing other than invest in one or two stock investments and be twice as well-off as he is having done no work or hard negotiating skills at all -- never mind the bankruptcies that ought to at least be investigated more thoroughly by those who think Trump is a sound businessman. Not to mention Trump Mortgage LLC, founded in 2006, when it was "a great time to to start a mortgage company ... the real estate market is going to be very strong for a long time to come." Well, that prediction exploded in everyone's face spectacularly (and the company folded, of course)
The claim that Trump has spent only $800,00 of his own money deserves some scrutiny, too. Official figures show that the Trump campaign is largely self-financed by loans from himself to the tune of $36 million or so. I suppose the nature of loans makes that "only 800k" claim technically correct, but massively misleading, no? External funding for his campaign amounts to very little, it is true (Jeb Bush had something like $100 million in SuperPAC campaign support compared to Trump's $3 million). But that's the point. The costs of the Trump campaign have been funded to a great extent by Trump himself, and his total costs have vastly exceeded just $800,000. Somehow or other, he proposes to pay the rest back to himself...
Turning to the Muslim immigration issue, how is that constitutional? I'll be cautious not to call it definitely *not* -- apparently there are differences of opinion on the issue so it would presumably have to be tested in court, but even people who claim it may be constitutional still condemn the idea:
http://www.nbcnews.com/politics/2016-election/legal-scholar-trump-s-muslim-ban-may-be-constitutional-n484981 . And they'd be right to do so. Most modern terrorists are Muslims, but almost all Muslims are not terrorists. It is simply ridiculous to assert that being Muslim is enough justification to bar someone from any country, not to say offensive and degrading to those already in the US.
As to the rest, I agree that Trump has done a superb job of tapping into the disillusionment many people have with the establishment. I think Cruz's demise this week proved that beyond any doubt, as Cruz was as anti-establishment as they come and still got trounced (thank goodness). How far does that disillusionment really go? I don't see it going far enough to win him the presidency, although he's spent the last nine months surprising everybody. He's surely too polarising to appeal to the moderate voter. Even many Republicans still won't back the heir presumptive. Whether they will turn to Hillary "I'm not inspiring at all but at least I'm not Trump" Clinton is less certain; perhaps 2016 will simply see a huge drop in turnout. I don't see how anyone can say that Trump beating Clinton is a certainty while keeping a straight face, although it's possible. But Trump has lost as many people as he gained, and how can he win them back?