That's nothing new but human nature.
If a gambler wins big, he does not win just the money but your friend in him (the person you knew) loses against that gambler. And he thinks that the society may come and ask him for money because he now has that class to lend people, but he doesn't want to. So he decides to stay away from his friends thinking that it'd be better to sideline them and enjoy his life on his own, with some new friends of his category.
We can see that human nature becomes visible when people win. Indeed, human nature is what we see.
A human being with money earned from anything including gambling will avoid from losing friends fellow gamblers, maybe he does not want to lend money or he asks for money on him, better enjoy with family than friends, this is not strange there are many in our circles like that when someone has earned big money.
Don't be surprised, even friendships can be broken because of money.
I think that depends on your friend. If you know how your friend will react, then most likely you will ensure that your money is safe, especially when we're already talking about millions here. Not all your friends are real; that's the reality. Even if your family might betray you, how much more a friend?
That's just normal; people tend to overreact when they have a lot of money. They make sure that they will be able to protect it. As they say, money changes everything, and in this case, money has become more valuable than friends.