Not true - at least not for the business aspect. The most successful buisness people that I personally know are super nice people. Like, omfg-mindboggling-nice. Maybe there are tons of people out there who get to be successful by being jerks, but I guess I've just never associated with those kinds of people.
Being nice doesn't have to mean that you're a pushover. And the biggest factor in winning or losing in anything in life is confidence rather than niceness.
Those who lack confidence finish last, not necessarily people who are nice.