Because many people only support freedoms for themselves, the second someone else wants to do things different than they would they get angry because they don't understand why anyone would think differently than them.

Also they don't ever have to worry about becoming young again so they literally never feel the consequences of their ideals and actions against kids. They feel safe in completely dismissing concerns and actual reality because they are so far removed from it and can cling to whatever imaginary view of the youthful world they made up.