To the well-intentioned advocate of welfare that will seem beside the point. No good answer has ever been given. That shouldn't surprise anyone, because there is no good answer. You either own something or you don't. It makes no sense to say you own your income until someone who needs money comes along.
All theories justifying welfare are rationalizations for theft.
It has been argued that if each person is to have a right to life, he must at least have the means to continue living. Welfare, so goes the theory, is intended to provide those means. The error here is in how the right to life is construed. It can properly mean only the right to take life-sustaining actions that do not violate the rights of others. If it is argued that it means instead the right to sustenance provided by others, we have a bizarre rights theory that produces conflict between people.