"I'm going to go back to doing just what I did before..."

It seems that this thought depresses Santiago. It seems that the novel is arguing that a certain type of person, like Santiago, is built for realizing his personal legend, and another type, like the crystal merchant, is not. Or maybe this is an issue of age? The merchant is too set in his ways to actually go to Mecca. And maybe this is also like that saying "You're only as old as you feel." If the merchant "felt" younger, he might be the type who would be willing to go to Mecca. He would never have entirely lost sight of his Personal Legend. (It seems like the novel is saying that you can't realize your Personal Legend by playing it safe. Your Personal Legend can't be to just be a really successful crystal salesman or sheep herder.)