Did any of this sites achived success in its field?
Success? When did YouTube.com actually start to make a profit?
Like every other online success story YouTube.com's success was followed by 1,000s - if not 10s of 1,000s - of copycat domain registrations. However, if a company as savvy as Google is having trouble making a profit "with the concept/domain" I somewhat doubt that any other person/entity would find themselves making a profit just because they named their site ()Tube.tld or You().com.