Minimalist posters explain complex philosophical concepts with basic shapes. Even if we define "feeling better" as a benefit, it does not logically follow that just because one receives this benefit as a consequence of performing a good act, that they performed it in order to obtain that benefit, and not primarily to benefit someone else.
(And even if "feeling better" was a benefit to the person making this sacrifice, it's not a benefit he or she would he able to enjoy for very long, since they will be dead.) Your argument, therefore, assumes a premise that needs to be proved: that people only do good (or anything at all) for their own satisfaction. Gotes.jpg (JPEG Image, 1324 × 1101 pixels) - Scaled (60%) The Nature of Emotions.
Complete relationship chart between psychological ("personality")... - StumbleUpon.