Thanks for breaking it down for me like that. I didnt realize that each race had such a huge difference in prize money. Still seems odd to have one race worth so $ and others worth pretty much nothing.
By far the biggest chunk of each race's purse comes from the track itself. Since the Daytona 500 is essentially NASCAR's Super Bowl (it's the only race where the winner loses the car for a year), and by far the most-popular race (actually 2 races; one of the two Gatorade Duel 150 qualifying races and the Daytona 500 itself), it can offer much more than any other race.