Why doesn't anyone like me?

Every person in my life makes me feel like I'm just someone they use when they are bored, and when they have nobody else.
Because when they have others or something else to do they are ever here for me. I'm everybody that comes into my life, and who is already in it treats me this way. 
It makes me feel worthless and it hurts so much. No one truly cares about me, I'm depressed and feel alone and I'm never really going to have anyone who doesn't make me feel this way. What do I do?