There is no guarantee to that and to all of course, the house can simply tell you they lose huge amount of capital including yours and you may never get responce when you ask for records. If you are into gambling already, you might as well just create your own casino. There is a crypto that will allow you to create.
The house could cheat by disguising themselves as a player and win in their own site however most of them are actually honest and it is part of the risk that you cant eliminate so you should just swallow it. Every investment isnt risk free and there is no way that you could hve a risk free investmend out of nowhere