Who makes a living trading baseball cards?

Some people just have a gift at making money, you know? My old Kenpo instructor had that gift. He was a full time martial arts instructor, but he ALWAYS had something going on the side. Somewhat recently, it was baseball cards. At first, he picked up a couple of them for his young son. He wanted to start a collection for him. Then he started looking up cards online and seeing what they were selling for. He then started looking up what cards were listed for in card value books. The genius that he is, he was basically memorizing what most cards were worth in the book and what they actually sold for, then he started trading, buying, and selling cards. It was amazing. He would find people to trade cards with and by the books, he would lose money trading to those people. They, of course, thought they were getting a great deal, but in reality, he knew what every card was selling for on ebay and the like, and he knew that he just made money off of them. Sometimes, he made hundreds of dollars in a single trade. He did this for over a year and he estimated that he was able to pull in about $50,000 by doing this in that one year. Of course, I wouldn’t recommend this to anyone as a side job because the man never slept. If he wasn’t actually wheeling and dealing, he was researching and memorizing what cards were booking for and actually selling for. You’ve got to have an amazing memory to do that kind of thing. Very rarely would he have to resort to looking something up in a book or online while making his deals. This made him all the more dangerous. Seriously, he’s a scary man to deal with…both in business and in the ring. I’m a little scared right now just writing about him.