Mark Cuban explains why he soured on Donald Trump

Billionaire businessman Mark Cuban explained in a statement posted to Twitter Thursday why he drifted away from Donald Trump after initially expressing excitement about the real-estate magnate's candidacy.

The owner of the NBA's Dallas Mavericks and star of ABC's "Shark Tank" said he "liked Trump's honesty because it was different" and the Manhattan billionaire "had a chance to change the business of politics" as a result of it.

"What I didn't realize he was missing at the time was a complete and utter lack of preparation, knowledge, and common sense," Cuban wrote.

He added that he "made the mistake" of assuming the Republican nominee would have "some interest in learning and keeping up with world events" and that he'd make an effort "to learn what he didn't know."

"I obviously was wrong," he wrote. "I can't say it enough that learning how to learn is one of the greatest skills anyone can have. It's why I advocate that everyone go to college. I love being challenged and defending my positions and, when I'm wrong, learning from the exchange. It makes me smarter and better as businessperson. That's the key difference between us. Trump never takes on the intellectual challenge. He doesn't even try. He just talks about having a good brain. :)"

A Twitter user called Cuban out shorty after he posted the statement for using the word "honesty" to describe his earlier thoughts toward Trump's candidacy, asking if Trump's promotion of birtherism against President Barack Obama for five years "wasn't a tipoff?"

"Honesty wasn't the word I should have used," Cuban wrote. "Unfiltered would have been better."

During Monday's presidential debate at Hofstra University in New York, Cuban was given a front-row seat by Hillary Clinton's campaign, as he's become one of her most vocal surrogates along the trail. The Clinton campaign called it the "best" seat they had available.

Giving his thoughts on the political slugfest, Cuban said afterward that didn't believe there was "any one top moment," calling it more like a "sporting event" in which "one team got way down and they kept on being combative to fight back."

"She was cool, calm, collected, and he was flustered," he said. "He was really, really flustered."

Cuban has been a Clinton supporter since he endorsed the Democratic nominee at a Pittsburgh rally in July, and he has ripped Trump repeatedly on social media and in interviews, calling him the most "dangerous" presidential candidate he could imagine during a recent interview with Business Insider. Cuban recently offered Trump $10 million to hold a four-hour policy debate with him.