I think luck does exist, but not as an entity, but as a consequence of "choice". When there are different results for one event, luck does exist. Well there is different types of it, as for exemple in poker, as we take it live, the cards are determined from the time the dealer starts distributing them. While in quantum physics, it is know that a system isn't determined before mesuring it, as all the possible ways exist at the same time, until we measure them. In the first exemple, the luck is due to lack of information, and in the second is due to a physical consequence of measurement and interaction.