Winning the lottery sure seems like a good way to ruin your life. It'd be interesting to know how many people, if any, are actually happier a year after winning than they were before they won.
Maybe human beings just aren't all that good at figuring out what makes them happy.
In chapter 47 of Sense and Sensibility, Elinor Dashwood very insightfully diagnoses this problem in John Willoughby. Austen is a very, very keen observer of human nature.