People aren't buying the lottery tickets. They are getting them free for their wager in multiply BTC game.
Since they are still sending promotional emails containing WOF spins, people also have the chance to win lambo tickets through WOF spins.
There's around 0.1% chance to win lambo tickets each time you spin the wheel of fortune.
They also had a promotion in which people could get lambo tickets through free rolls for a limited time.