There's nothing wrong or stupid about helping others. There's even nothing wrong with sometimes putting personal benefits aside in favor of group benefits. These are good, admirable things. Delaying personal benefit is the foundation of any stable society.
But do not confuse altruism with outright stupidity. While collective gain is good, do not value it so much that it ruins personal gain. There's no point to helping a collective which does not help in return. Or an individual.
So while it's good to help friends, it's also good to have good friends. The person that you always help and never seems to offer anything in return, is not a friend. Friends are mutually beneficial, not one-sided leeching interactions. At times friends may ask a bit more and may give a bit less, but when that becomes a pattern, it should not be ignored.
I'm sure you have your stories of lazy friends, stupid friends, bad guilds, all manner of situations which seem to make friendship and altruism look stupid. Notice the adjectives? Lazy, stupid, bad. These are not inherent characteristics of all friends or groups, but of specific groups. To avoid all connection is to be as stupid as those who embrace all connections.
Maybe you had a bad experience in high school or middle school with all the cliques and arbitrary exclusion. I remember the annoyance of drama. My solution wasn't to reject all friends and all groups, but instead to have good friends and join good groups which did not sink into the mess of stupidity which dominates young social interaction.
It just is
Altruism, friendship, kindness, being helpful; these are generally good. Like water. I'm a fan of water. Drowning isn't so good. Should I reject water to avoid drowning? Of course not. That would be as stupid as swimming with an undertow. But I avoid times and places where I cannot safely swim. Similarly, I avoid damaging social relationships.