Can you completely trust
online poker sites? Of course not lol. This is especially true for US online poker players.
Give a group of people the opportunity to make some extra money at the cost of others with very little or no risk and 9 times out of 10 they're going to take advantage of that opportunity. Regulation exists for a reason, the problem for US players is that any site you're playing on has little to no regulation.
You can trust theses "US-Friendly" poker sites no more than you'd trust a stranger off the street.
When it comes to cashing out your money you usually shouldn't have much of an issue, especially if you use crypto.
I think the real question lies in the poker software and algorithm. According to
pokerstars CEO, designing an accurate poker algorithm is literally impossible using software alone. Pokerstars using a sophisticated hardware system along with random user interactions within their poker RNG algorithm. What are the chances that the average small US
poker site has anywhere near this kind of technology?
So even if it's not the site's intention to have flawed poker RNG, chances are they do anyways because they can't afford the equipment to design a more accurate algorithm. Many people still manage to beat the sites but just remember that you're playing at your own risk and playing online for
real money does require that you put a certain amount of trust in random people you don't know and who's product normally has little to no regulation.