Provably fair is basically an algorithm consisting of cryptography and hash functions to derive a number.
Most of the gambling sites include 3 major elements into their provably fair algorithm which are server seed, client seed and nonce.
Its known that provably fair is by far the best way to derive a random number. Its trusted by most of the gamblers in the community.
Something like this is how I interpret what Provably Fair can be, a strong algorithm that is completely impartial, it is also widely accepted throughout the casino and betting community, and if it has that acceptance it is because it really is very reliable.
I had that same curiosity years ago, at the programming level I have no idea how that code can be, Prabavly Fair is the best way so that no game can be manipulated. There will be many who will try to beat Probavly Fair, but it is impossible. And I am sure that many players will have had that doubt.
Even I think there will be people who would be trying to beat provably fair system but would have failed since it is not so easy to do it.
There are few people who have built some generators which creates a simulation of X bets and gives us the results.
Here X is the number we provide as input and then people refer the results and use it as a reference for their next bet.
I wonder how that works out for them but they have shown it to work nicely in their scenarios.
Still nothing can really beat the provably fair algorithm yet.