Young people are more idealistic about how the world should be but less realistic on how the world really is. Over time life experience and responsibilities like work, family and a mortgage will creep up on you and slowly swing you to the safe world of moderate capitalism and conservatism.
Yesterday on the news it was said that the Green parties in Europe have the future because half of the young voters (18-25) voted for progressive parties, but they forgot that in 5 years they will all be at the age of starting a family and will vote much more conservative.