I think this really happens in friendships especially when they are gamblers who when they manage to get a big win in one of their sessions it is not uncommon or maybe even common that they will avoid their closest friends especially those who are also gamblers, and the reason is that they don't want their friends to ask for a share of the winnings so they hide information about their success and pretend not to have money.
This scenario also happened in my circle of friends where at first I did not know why one of my friends suddenly avoided me and after that I heard from one of my other friends who told me that the friend who avoided me had just won a big win in the type of slot game and this happened several times which made me really did not expect that he would act like that even though I had no intention at all to ask for a share of his winnings.
In fact, even the smallest win is worth celebrating with friends, but perhaps that only applies to gamblers who are only after pleasure, not the profits they get from gambling. I think it's true, that not all friends will ask for money or a share of their friend's winnings, so basically avoidance is more precisely called reluctant to share. Meanwhile, in a more intimate circle of friends actually avoiding when getting benefits is rare, because they often get reciprocity from others.
On the other hand, there are many cases where someone is reluctant to share, and that is not wrong, but it is also appropriate that he is not invited when we celebrate a victory with other friends. Personally, try as much as possible to not borrow money from friends who are lucky in their gambling, because it can ruin their winning momentum. Someone definitely has a tendency to share without us needing to ask, at least to treat us to delicious food.
Yes, it's true, it's more likely to say that celebrating winnings with friends would only be done by gamblers who don't really expect to win in their gambling or those who come with a priority for fun or entertainment so when winning is not a priority then when they are lucky and manage to get a win then it's reasonable to assume that they wouldn't mind celebrating their winnings with their friends. In fact, I've honestly had an experience where I was sitting at a table with someone else and when he won he treated me to some food and drinks, even though I didn't know him at all but he invited me.
On the other hand, I believe and I have proven that kindness is always rewarded with kindness, I experienced that when I did not have any money at all but one of my friends suddenly sent money to me by saying "taste some of my fortune" which scenario made me not hesitate to share some of it back with him when I managed to get a win and this reciprocal scenario applies in any case including gambling.
On the other hand yes it is true that it is not wrong if someone does not want to share the proceeds of his winnings because after all it is his right, but maybe there are some people or gamblers who sympathize with other fellow gamblers and I think this depends on the personality that the person has but obviously sharing can increase the relationship in friendship, and other things yes as you said and it is true that if for example they want to share it then they themselves will definitely offer without the need to be asked.