Reason #4 like Bovada:
Online gambling is largely unregulated in the U.S. That means the casinos serving U.S. players generally don't answer to anyone. If you have a problem with a casino (like they won't pay you), then you're usually out of luck. I can't count how many players have written to ask me for help because they didn't get paid by some other casino. (Not that I helped them—if a dodgy casino won't pay you then you're on your own.)
That's why the most important thing in playing online is to pick a good casino. The good ones know they make more money with fair games and consistent payouts, because that ensures repeat customers and good word-of-mouth referrals. It's no coincidence that the most successful online casinos are the ones that focus on their customers.
But some casinos aren't so smart. The stupidest ones actually rig the games, promptly get blacklisted at sites like Casinomeister, and then their business dries up. (It's pretty easy for watchdog mathematicians like the Wizard of Odds to determine whether a casino is cheating.)
Cheating is rare. You're more likely to have a problem getting a payout. Some casinos try to find excuses to not pay winning players, especially players who have won big. And again, since online gambling is unregulated in the U.S., if you can't get a payout from a casino, then you're usually out of luck.
So all this is another reason why I advertise Bovada, and have done so for over ten years. They use industry-standard software, it's absolutely fair, and players get their payouts, consistently. I have a choice in whom I advertise, so I purposefully picked a casino with a good reputation where I'm confident my readers will have a good experience.
To be clear, Bovada's not perfect. Once they got duped by a vendor (Betsoft) who provided progressive slots whose jackpots weren't winnable. When I discovered this I alerted Bovada, and they pulled all the Betsoft games from the site, but I thought they were slow to do so and didn't offer proper restitution to affected players. Still, even with this incident, their overall history is better than most; as just one example, there are many other casinos still offering Betsoft's questionable games.
Another good thing about Bovada is that they allow me to mediate if one of my readers clicks over to them, plays the games, and has a problem they can't get Bovada to resolve. Believe me, I wouldn't offer that service if I got more than a trivial number of inquiries over the years on that topic.
Bottom line: I'm confident that Bovada is fair and safe. You might have a good experience with another casino...and you might not. I trust Bovada, and that's why I picked them.