It's more risky than purchasing bitcoin or SHFL token directly. Mining bitcoin or wagering to get SHFL token contains many uncertain things while with direct purchase, it's more simpler and less risk too.
It would be risky only if you force yourself to play more than usual and gamble more than what you can afford to lose. The SHFL tokens you receive for playing games on the casino is a form of reward just like the loss back and the alike bonuses and must be treated as such.
If you want to invest in SHFL then, as you suggested, just buy it.
