Few men realise how big the problem is, because they are seldom the target of harassment themselves. Even men who are opposed to harassment may not think there's anything to get concerned about. But there is. Some women cannot pass through a day without encountering unsolicited comments, requests for their phone numbers, touching, grabbing and so forth. They can't just go about their business without having to ward off unwelcome approaches.
Some women avoid public places because of harassment.
At the more serious end of the harassment scale are assault and rape. Sometimes a pleasant comment is followed by a hostile one. Women may fear that minor harassment is the first step towards a more serious attack. Women deserve to be able to go about their business just like men. Public spaces should be for everyone without discrimination.