Why do some Europeans think the European (White) race is the superior race?

Because for centuries, the Europeans conquered the known world, because their technological acceleration was superior to the majority of the world at that time. (The exception being China and Japan, who had superior technologies, but smaller populations and more isolationist attitudes)

There is no "superior" people.

Because 500 years ago white men established themselves as superior, enslaving the black people. This ideology is still true today, with white people taking up over 95% of the jobs as CEO's, Managers, and other high ranking positions.

That is not a European trait, but a human one. I've lived more or less everywhere and everywhere there are people that find their race / religion / belief system superior. As a matter of fact all people believe theirs is the only way of being.

Because they created the biggest and nost powerful civilization in the history of mankind.