The fee isn't just to tell you which trails you can and can't go on. It pays for the maintenance of said trails and paved roads. It helps pay for cleanup and law enforcement out there. It's not all bad, because if you get hurt, they are the ones who come help you. It's mostly for maintenance and general upkeep o the park. Besides, people are less likely to be destructive in places they have to pay to get into. Free spots are much worse in quality.
The difference between stupidity and ignorance. Ignorance is doing something wrong and not knowing better. Stupidity is knowing better, but doing it anyway. Don't be stupid!