Have you ever felt as if you are worth nothing?!

Have you ever felt as if you are worth nothing?

If so, what made you feel like this?
If not, what WOULD make you feel this way?

i feel like nothing from time to time and the reason is that people just completely ignore me or speak to me as if i am the most stupid person they had ever seen..around arrogant people i mean...my mum sometimes does that too...it is really unbearable