Just a thought:

If helping others gives a meaning to your life
then you depend on others to be worse off
than yourself so that your life can be meaningful
to you, you then have a purpose to your life as others have a purpose too ... 
the ego being human that can only boost your ego,
but if you are coming from an

'inner purpose' you are then coming from

awareness where the ego cannot survive and this applies to all we do in life.''