I didn't say there was an issue with it and as you say, it is pretty much business 101 - buy product, ensure you get more for the product that you paid for it.
Some (maybe all, I haven't checked) are also incredibly open about the details of the draw with every ticket listed out to view after the event so you can even calculate how much they made (gross) on that particular prize.
The point I was making is that you are funding the lavish lifestyle of some dude behind a flashy website and the vast majority of people will get Jack in return.
EDIT - lets also be clear on the numbers, these guys aren't getting out of bed for £5k profit on a £20k prize. I just looked up the entry list on a £2500 cash prize, the ticket income was pennies short of £4k. £25k cash prize = £36k of tickets. I'd expect the gross margins on the cars to be higher due to the additional costs involved with an actual prize rather than a bank transfer.
EDIT 2 - I've taken a small sample size but about 60% gross seems to be the margin on the cars (third edit because I can't do maths

).