This is actually an abjectly untrue statement. Trump, by and large, was a failure at real estate. Aside from his illegal practices (fraud, not paying subcontractors, not living up to contractual obligations, running afoul of discrimination laws), he had such a poor track record of success, that his "core business" could no longer garner financing from just about any legitimate financial institution (hence, his reliance on shady / Russian / mob monies, as no traditional financial institution would back him).
The guy was a failed developer, repeatedly. No one had any faith in him. I am in real estate, and was in NY Real Estate until post election, and this was common knowledge.
Now, he was a great brandman / promoter... and those Hotels are not Trump real estate ventures (his repeated failures and bankruptcies eliminated that opportunity), but rather a brilliant job at promoting the Trump brand - something that he did exceptionally well, especially after/in conjunction with his latter career celebrity.
TL;DR - Trump was not a successful real estate developer, quite the opposite. But he was a great brand ambassador and promoter, buoyed by his success as a TV personality / entertainer/