It can definitely work (depending on luck of course).
on our last cruise (first comped trip and first time really playing serious in the casino), we racked up 5,800 points on my account and 3,700 points on my g/f’s account.
Total loss was around $800.00
That got us both to Prime, so 2 trips to be booked later, plus our instant certificates got us a 9nt New Years cruise on Odyssey and a 7nt Egypt cruise, both balcony rooms.
She has received 3 balcony random offers, and I’ve received 1 balcony and 2 suite offers.
If we get nothing else from the play, that’s 10 cruises (balcony rooms or higher), for $800.
Worked well for us, but YMMV.
Good luck.