It's very bad to discourage people from doing something that you are benefitting from, because I think it's just greed or wickedness if you do such thing. I think you don't have to bother about it, especially if it does not affect your own income, rather you should encourage them to do the same, so they can make some income for themselves. In my opinion I think most people do such thing, because they feel they don't want much people to know about how they make their income and also think that the more people get involve, it's reduces their chances of making more income from it, so they rather discourage other people from doing it. That's just an opinion, but I still think ots not enough reason for anyone to do such thing.
It is bad in whichever way we may look at it, the thing is why discouraging the same people that you are not going to always be present for them when their financial needs will be calling, teaching people how to fish is always better than given some one the fish. Sometimes life is very simple, some one you helped today can also also help you tomorrow, no one knows what tomorrow may be. If you have an opportunity that others can benefit from, don't be greedy and selfish, tell others and trust me the world is not going to come to an end just before you did that and you are going to die, there is always a peace of mind when help someone truth be told.