The thing that tilts me is how nobody, especially the dealer, told him to stop being on his phone DURING a hand, which he did multiple times every single session.
Everywhere I play has a "no using your phone while in a hand" rule. It doesn't get enforced 100% of the time; I've seen plenty of people be on calls, text, internet, watch sports, etc while in a hand (heck, I'm often watching a UFC fight), but that's usually only once or twice a night. If it's more than that, the dealer will ALWAYS ask the player to turn off their phone while in a hand, at least if the player is interacting with the phone; they're a little more lenient if someone is obviously watching sports.
And I've NEVER seen someone hide their phone under the table while in a hand. It's always up to their ear (talking) or in their hand above the table (texting, interneting) or on the rail (watching sports).
I've even been at casinos that have a "no phone at the table, even while not in the hand" rule. You had to stand up and leave the table to be on your phone. A bit extreme given how addicted people are to their phones nowadays, but the dealers actually strongly enforced the rule; they didn't just let it slide.
I can understand how the other players wouldn't want to call him on it, just like people often are afraid to call the clock on others, but it's literally one of the dealers' jobs to enforce that rule, and they do so at every other casino I've played at, at least if it occurs this often.
It's inconceivable to me that he was looking at his phone BELOW the table in EVERY SINGLE hand he won but was never told to stop.