Shame we didn't get the actual author of the Art of the Deal, Tony Schwartz. Trump had it ghost written. I read it years ago and thought this guy is pretty cool, not realising it wasn't Trump.
In 1987 the real Trump was off in Moscow being groomed by the Russians.
Approximately all of those kinds of books are ghost-written. People with money who aren't otherwise authors only very rarely write their own books. It takes a lot of time, and business "leader" sorts especially are extremely comfortable delegating that and then putting (only) their name on it.
Trump's is unusual in that it's widely known not just that it was ghost written, but who did it. Often the real writer's name isn't known, and we can only guess at whether it was ghost written (again, the answer is almost always "yes").
In 1987 the real Trump was off in Moscow being groomed by the Russians.