They aren’t safe with police either- there are dozens of accounts of cops assaulting prostitutes (and hell even not prostitutes). By decriminalizing it we allow prostitutes to have an opportunity to find safety and protection under the law without fear of prosecution for themselves. Some government regulation could do good in the way of brothels.
I feel like it would decrease it- more opportunities for people to join the profession without having to go deep underground, opportunities to report assaults and violence to the police without fear of prosecution for themselves, and possibly brothels to create a safer cleaner environment.