As others have said, it's TOTAL COIN IN. Not "I took $300 onboard and got a free cruise!"
You took $300 onboard, won and lost a bit for a few days and left broke. That's a different calculation. You win a couple fat piggies with your $300 and feed it all back, that's why they want you back.
Take $300 in cash and just play table minimum blackjack. See how many offers you get.