The big reason is daytraders usually buy on margin , hoping that they will reap higher profits through leverage. The unfortunate side effect of buying on margin is risk of higher losses. Trying to pick a stock that will rise over the next couple weeks is hard enough. Newbie investors who think they miraculously can pick stocks over a few hours or minutes are absurd. I don't care how many strategies or systems are developed, this isn't a viable option for the vast majority of investors.
Lets get back to our dry-walling friend.
You can guarantee each booth at the convention was shmoozing this guy to wits end. Each of them standing to profit if our friend start daytrading with them whether he is capable or not. Lets hope that our friend resists the temptation to gamble away his hard earned money. The book focused more on convincing readers that daytrading is a good thing than actually giving any solid techniques. Something just isn't right here.