Why Do People Gamble On The Internet?

He could be just playing for entertainment or to pass time. Poker is just a game and can be fun like any other game if he is disciplined and the game is not disruptive.
 
But, gambling can also be very addictive. The word "internet" doesn't make it less dangerous. In fact, access to gambling on the internet has increased gambling addictions across the world.
 
If he is losing money that affects your family’s ability to pay the bills or he is neglecting his family, then I would say you would be justified to be upset. But, anger is not the best response to this issue. Instead, you should focus on how you can get him to realize his addiction and seek help.