It can be. If you believe that you cannot be truly secure in your freedom and well-being unless everyone around you is also secure in theirs, then helping people could be seen as "selfish". The problem is that we use the term selfish to mean whatever dickheaded move looks like it will net us some short term benefit. Without the ability to see all the indirect consequences of these selfish actions, we don't notice that the aggregation of them actually diminishes our overall well-being. Socialism, it could be argued, is based on selfishness as well, but paired with a recognition of our limited foresight and an attendant tendency to err on the side of mutual support rather than ruthless competition.