The same people win over and over and over again. My guess is that they either buy all their ticktets at once, or what I suspect, is that they literally buy one ticket here and there until they've bought all 500 tickets (they probably split it up evenly throughout the course of 7 days so they're buying like 70 tickets a day.
I've spent probably 50k on the lottery and never won, but it was always when I had extra money to blow. I personally would advise against playing it, they don't call it a poor man's tax for nothing.