You do a lot of travelling. That's books one and two. But the majority endured years of rejection before they made their first sales. Some of that majority, no doubt, just had to practice their craft until they were good enough to be published. Many of them were perfectly good writers, though, who just had to wait until their number came up.
Publishing is a crapshoot.
There is absolutely no correlation between early success and literary value. There is a weak correlation between early success and the probability of making a living from writing, but the reasons for that are clear. I'm in the minority. But my most successful novel, The Forever War, was rejected by eighteen publishers before the nineteenth picked it up. You ask if a person can determine whether or not he has the talent to make a living at writing.