We never knows what is his reason avoids his friends after his winning. Many reasons can makes someone change and avoids or left his friends after he had a big money. One of the reasons is because he doesn't wants his friends comes to him and asks for the money as their part because they are his friends. That one popular reason that happens in many place so someone who had the money will avoids his friends. But there will be other reasons why he did that but he doesn't wants to explain his reasons. Maybe he will tells the reason to other friends or family because they don't related to his friends so they can accept his reason. Maybe his friends will jealous with his winning or else but his friends should accept what his decision and lets him do what he wants with his money.
That's true, so I won't judge easily. Same scenario occurred on me before and my reason for doing so is because my friends are fake and they don't give a tip to me when they win. there are still circle of friends who are not based on money and each member talked about this early, so that no hard feeling are felt once they are aware that some of their friends suddenly got a decent amount.
Many are curious to know the reason, so it's better to disclose it, so that its easy for others to move on. This is beneficial for each of us. Telling the reason to other people and not to our friends seems funny but some of them can still tell our friends. There is no escape.