Very funny but it's reality, there are annoying people who will call themselves as your friend as they need something from you, after you win huge amount of money, expect that there are many people who will try to claim as your good friends, though in terms OP's situation, it's so sad hearing people talks about someone who at first is always with them enjoying the games but after winning huge money got disappear and no longer wants to communicate or already put a gap between him and his old pals.
Yes, that does happen, and we have probably experienced it up to now, so we really have to choose between making friends. Many friends will come to us when we are getting something, say winning the lottery, and congratulate us. But actually, many of them are not sincere in saying congratulations, but there is something they want. We have to be more careful in conveying things to people close to us and only tell it to people who are really our close friends so that only a few people will find out. In @ OP's situation, there may be a misunderstanding between them, so someone talked about someone who was always together at first, but because he won a lot of money, he avoided and disappeared from his friends.
Not only strangers or people you don't know, but your relatives, close ones, and so-called friends will make your life hell if they come to know that you've won something significant from gambling or something else and even those who never talked to you or paid any attention to what you do or how you are will come and try to be friendly with you just because you have a lot of money now, that's how the world has become, everyone out there is selfish these days except for your blood relations but even some of them are greedy sometimes, apart from your mother and father.
This is the reason why most people don't even tell their close ones about their winnings even if they win a significantly high amount because they know what is going to happen. I also suggest people do the same, never post statuses or stories, and let people know about what you've achieved, there are very less people who will be genuinely happy for you but more will be jealous and have bad eyes on your success and achievements.
That's why we have to choose anyone who can know about our big win, and they can really keep the secret so that only a few people know about it. Indeed, nowadays, many people easily change because of money, so we have to be more vigilant in establishing friendships with the people around us. And we also shouldn't easily trust people we have just met because we have yet to learn what their true character and nature are like. We could share the story of our win with our family and friends who are truly friends so that only with them we will celebrate the win.
We shouldn't tell people about the big win we got, even people we don't know, rather than endangering our safety because there will definitely be people who have evil intentions towards us and want to get the winning money. And, normally, more people will be jealous of what we get, so they will tell us about bad things or speak ill of us, and we don't know about it.