What is wrong with people?

So my library had the unfortunate experience last night with a lewd act in the Children's Library. It involved a man in his twenties - and he was going solo. An adult patron witnessed this and alerted a staff member. Thank goodness there weren't any children in the area at the time. Seriously, what is wrong with people? More specifically what is wrong with men? Why don't we ever hear about this happening by a woman? It's always men.