For me, the concept of luck is purely descriptive. Luck does not explain why something happens to someone. If someone wins the lottery we can say that he is lucky. It is not, however, because he is lucky that he wins the lottery; rather, his winning the lottery is what his being lucky consists in. To say that he is lucky in winning the lottery is just another way of saying that it is very unlikely that he wins but he wins anyway.
Unless you understand luck to be some kind of mystical force that causes things to happen to people, you should not talk as if luck has causal power. Without such an understanding, it is nonsense to say of someone that because she is a lucky person, it is more likely that something good is going to happen to her (or that because she is an unlucky person, it is more likely that something bad is going to happen to her).
On my conception, a lucky person is simply a person to whom good things happen noticeably more often than to others. And a person is lucky on a particular occasion when what happens to her is good but very unlikely to happen. (Mutatis mutandis for an unlucky person.)