Although, I'd be suspicious of every single website you use. Don't just believe the provably fair, test it out.
Exactly. There are many gambling games which claim that are provably fair, but, they’re rigged. You just need to experiment with them, to determine if they're indeed provably fair or not. This applies to regular online gambling games which are controlled by a central operator. However, with the newest iteration of smart contract-based gambling games, it's nearly impossible to rig the game or cheat on it.
I've known of several online gambling games which rely on the Ethereum blockchain and are indeed provably fair. They're based on a coded mathematical formula which serve their purpose of being fair. Speaking of this, you should check out FunFair as it's based on the Ethereum blockchain with a few provably fair games.
To be safe, test out the game or simply read reviews about it, before placing your bets. If the gambling game is not rigged, then you can win if you keep trying. Just my thoughts