Sportsbook whoring?

[kimchi]

I couldn't find anything on the search, please link me if this has already been discussed (I assumed it would have).

I've seen sign-up bonuses for a total of around $10k on various internet bookies. The play-through usually seems around 3x the bonus + deposit. Since a payout of around 93% seems common (assuming I have no ability to pick resulst), then:

deposit $50K for $10k bonuses, play through $180k @ 93% payout losing $12600. So, unless I'm missing something, these bonuses are -EV unless you have an edge with picking your bets. I also assume this is unlike casino whoring where it's pretty difficult to (eventually) come out with a profit.

Please correct me if I'm wrong as I'm a complete sportsbook noob.