I used to do that pretty much the whole time I was in high school. I'd say it was my way of distracting myself while waiting for things to get better.
One of my favorite questions for getting through tight spots is, "How do I [or you] know that?" What I'd like you to consider, happycheeks, is: is there any way to tell whether you're a "loser" or not besides your saying so?

By the way, if twenty other people happen to tell you you're a loser, that's not the same thing as "I'm a loser". That's "Twenty people just said [whatever they said]" -- no connection, unless of course you decide they're right and you'd better agree with them.