I wasted $25 on seeing Mark Cuban inflate his ego in-front of a bunch of people

I saw Mark Cuban speak at the Merchandise Mart for $25 in Chicago. It was literally him pumping himself up for an hour, not really sure what I expected.

At one point he says high frequency trading is wrong and serves no purpose to the retail investor. He forgets to mention that he made 99% of his money dumping $5Billion dollars of worthless stock to Joe Public (valued at ~$10,000 user). He could say no one knew it was worthless, but he dumped the stock as fast as legally possible in what is called one of the best trades of all time.

How is making $5B dumping worthless stock on the public better than high frequency trading, which very debatably adds value to the markets?

I can't wait to buy Mark Cuban's book so I can never buy toilet paper again.