It's always something good to find a bug a d report such as appropriately needed, if we are to consider the gambling sector for now, we are not having more of the people interested in this and it's all because they have experience low rate from how this is actually happening, you may hardly get to find one, gamblers will be so focused on having their fun in using the casino than looking for bugs around when majority are even after winning their bets, we can therefore see this that it's not common and that rampart as before that they were being discovered, however, we shouldn't still relent from finding more because they still exist.
Mostly players don't have much knowledge regarding those bugs and they aren't bug bounty experts either but sometimes a player with sharp mind can find some easy bugs that aren't related to code but can be accessed via the UI of a website. It requires specialized knowledge of hacking and programming to find the bugs in a casino or a game that a casino offers and I'm really sure that most of the players don't even care about such bugs because they mainly play to test their luck and if their luck is good then they can easily win against the casino's house edge.
Let's assume if a player is expert at finding bugs then surely that player will spend more time to find those bugs rather than playing the game. I have noticed that very few players are interested in finding bugs in casinos and I have never seen casino sites to offer good rewards to those players or those people who can find bugs. But, it's a sure thing that if someone tries to help a casino by finding some bugs of their platform then they will at least get some rewards for doing that.