At the height of his wealth curve, he'd be viewed as a successful business man.

I guess you're using Research in Motion as an example of a company that went up and went back down, and are picturing some imaginary CEO, not Mike Lazaridis or Doug Fregin who were the co-CEOs of RIM, but are no longer with the company.

The difference from Trump is that this imaginary "Blackberry CEO" took a company that was worth nothing and then made it into a company that was one of the most influential in the world. That "zero to hero" story is something Trump never did. He started at the peak, with half a billion dollars he inherited / stole from his dad, and then he went down from there.

To be considered a "successful businessman" you have to make something worth more than it was previously worth. That's not something Trump ever achieved.

Jay Gould was considered a successful businessman because he grew up in poverty and then became a multi-millionaire (a billionaire in today's dollars). His son George Jay Gould isn't considered a successful businessman because all he did was inherit his dad's company and didn't meaningfully increase its value.

Fred Trump was a successful businessman because he made the fortune that Donald Trump squandered.