Being a URM helps at most schools that are looking to increase the diversity of their class. But if you are not competitive for a school chances are they will still get that spot filled with another competitive URM. Now to the question of should you still apply to a school you arent competitive for. I would say it depends, it depends if you have the money to spare and if you will work on the secondary questions as thoroughly as you would a school you have a good shot at. I also suggest you prepare yourself mentally of getting rejected from that school, actually prepare yourself that you might get rejected at any school so everything else is gravy.
Also Good Luck I applied to a couple of "Dream Schools" as well cant win the lottery if you dont buy a ticket.