The main reason to take the lump sum is if you want to do things that cost more than the annuity. For example, starting a company, purchasing a company, running a political campaign, giving a large donation (e.g. endowing a position at a university), etc.
Those are just a few of the ways a typical rags-to-riches lottery winner (with tons of encouragement from an entourage of friendly and helpful advisors) is likely to end up broke in 10 years, and exactly why I'd expect the annuity to be more profitable for them in the long run.
