As of the time of this writing, the wheel spin bonus costs 594 RP and the base awards are 32 BTC/Lottery/RP. Assuming you value tickets, RP, and BTC equally (for the sake of simplicity), it takes 18.5 rolls to get the equivalent amount back, if you only ever got the base rewards. However, rolls of base rewards make up 900,000,000/1,000,000,000 possible rolls, meaning you have a 10% chance per roll of getting higher than base rewards - 6% chance of 10x rewards, 3.98% chance of 100x rewards, and 0.02% chance of other rewards.