Opening a paintball field is all about... Location, Location, Location.
Oh, and incase I forgot, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location, Location.
If there is a site 10 minutes closer to the city than yours, they will take 95% of your business. If there is a nightclub, cinema, shopping mall, or other such site closer to the city than yours, they will take 50% of your business.
Oh and whatever profit you calculated you will make, divide it by 30, thats about what you will make.
But get the PERFECT location, and you will do great.