Hey Aluminium,
I know how you feel, but let me try to give you a little different perspective. First, sorry but it isn't directly related to paying him. I see that your brother is wasting his time with pc games, just as I did between 14 and 18. The reason why I was addicted to it was my lack of self-respect and the needed ego-push I got from playing. We all want to be acknowledged and feel good about ourselfs, and it highly depends on which way we go. I think, if you really want your brother to stop playing and start working his ass off, you have to stop making him feel like a leech. Instead, try to give him hints of the value of having success in business. Try to make him believe in himself that he actually can do it! See, as I was addicted, my father made me think I was the biggest loser on the planet. Of course, I tried to counter-act that push against my self-respect by playing and playing and playing, so I felt better about being good in the game.
However, if you make him believe in himself and offer support on his way, he'll be able to step up and get it. I know, if it weren't for my mom, who always believed in me and always told me that no matter what, I can do it... I wouldn't have had the power to go through and make a living with IM projects on my own.
So, pay the money and tell him you want to talk with him afterwards. Don't be down-putting and don't give him a lecture on what's wrong with him. He'll just block because of the emotional pain. Instead try to show him what's good about him and why he can achieve it. Believe me, it works 1000x better than the typical "You suck, grow up finally!". And that's not only my opinion, but scientific research also has shown that positive feedback ALWAYS works better than negative.
warm regards,
neocortx