This DEPRESSION, the disease talking. You do not have to believe this voice. (it can be a bit like the voice of addiction saying "go ahead...doesn't matter...prove you are a loser...". People here do care. Who says you have to make a "purpose" for your life? It is a journey---and we are all on it---and, in some way, we are all alone and yet all in this together.
Suggestion: force yourself to write down One good thought/experience, however brief----each day either when you first wake or before you go to sleep---this can be actual, a memory, or a wish, a good dream, movie, day in the life, Anything---