This is a kinda confidence vs arrogance debate really. To me confidence is the accurate realisation that potential negative outcomes of a situation ares compartively unimportant when there are greater potential postive outcomes(allowing more focus and thus increasing the chance of success) whereas arrogance is the belief that you can, and need to, be better than other people by either promoting yourself or defaming others. I guess the line can be thin between the two but confidence doesn't involve putting others down whereas arrogance does(whether verbally or just psychologically).

Now enough of this deep crap, lets party