There are some reasons why these addicted gamblers affect other people with their gambling addiction. One is the peer pressure. Probably one person in the group is addicted already into gambling and he introduced it to his friends. Out of curiosity, these friends tried to gamble and they got addicted into it since they see that gambling is fun. These is one of the possible reasons why many got affected into others gambling problem
It might be true among the young generation mostly
As the majority of adults have already been exposed to gambling at some stage in their lives, and if they didn't turn into addicts before, it is unlikely they are going to become such now, even if their friend or friends are going to try to reintroduce them to this activity. They may play for fun but then quickly lose interest and switch to something else. Unlike the coronavirus, gambling addiction is not that contagious
I think the same, however there is the possibility they can still affect their friends in many other ways, one of the most common is to ask them for a loan giving them the excuse they need it for food or rent and instead use that money to keep gambling, since we are talking about two people that were close to each other it is unlikely there is a writing agreement about the loan and as such it will be impossible to prove that it took place, which means the friend that lent the money most likely is never going to get it back getting affected in the process, also the addicted friend could steal from them to keep their addiction going.