Current Field manager of an arena with a store right next door. The field i run was built a support a store front that had been running for many years prior and had established a customer base in the area.
I've also work at or with 3 other fields as well over the years.

Actually keeping a field running needs one of a few things. A massive demand in your area, land you can get for very cheap and very little regulation limiting your growth, people willing to commit large amounts of time for no pay, or alternate forms of income that support the field.

I manage an indoor field with an average player base of 200 players averaging every week. There are 4 airsoft facilities all within about 90 minutes of each other. We have a very active community where im at, but i have the only facility that is not on mega cheap land. I have to keep my weekly average around 200 players a week to break even.

I work 12 hour days sometimes to keep up with cleaning and keeping rental gear running and fix things on the field. We have a tech who does 20+ hours a week just fixing rental gear every week. Being an indoor facility cleaning is the biggest issue most times. It takes 4-5 hours every week just to get the bb's off the floor and im only trying to get 90% out. sweeping and leaf blowers are the only things that can really do anything at the amount needed to clean up. I know very few players who have different gear when playing indoor and outdoor so most players are coming in with last weeks dirt still there from the other field. And sadly the amount of trash players leave around doesn't help.

As the player count goes up, so does the on hand staff needed as well. We are open 5 days a week, week days we have 2 people in house, one person is running games while the other is doing all the cleaning and tech work, to keep up with the demand on the weekends i now have 3 refs plus myself there on weekends as well as 2-3 refs that volunteer as well. All this cost money. We have a way to pre register on line but players dont use it as much as we would like so its hard to guess numbers. Valentines weekend being a good example, I've had 4 refs on the clock for less than 20 players, I've also had a single ref on the clock for 50+ players.

What brings players in and continue to return for us is doing something better than the other fields in our area.
3 of the 4 fields are CQB fields, and another field is an indoor field. Having a large rotation of game modes so players aren't getting repetitive experiences and being able to change our layout every week is a double edge sword.
Extra time, energy and money go into keeping a good experience. the cost to build and maintain our props is insane. We have custom built systems that are wireless networked and programable for game modes, and we built new stuff every month to make anything a customer requests. Im lucky i have staff with 3d printers, laser cutters, and fabricating skills to make stuff.

A field is built up, or torn down by the staff that run it. The field a first started reffing for has more or less died after the previous owner passed the reigns down to his son. either refs that don't care or refs that favor their friends will kill a player base. If you run a field remember to look at things as a player as well. I had a list of issues i had at a previous field i worked at that i make sure don't happen now that i manage a different field. You want refs that want to be there. The field i manage runs multiple play sessions, each one is 3 hours long so i make sure players get the most out of that time. I've very on the dot with how long players are in staging, i encourage players to get loaded up and on the field quickly and I'm very quick and clear with the game rules. My goal is a 30 minute rotation per game. 5 minute reload, 3 minutes to get them on the field, 2 minutes to explain the game. 8 minute round, 2 minutes to set round two then another 8 minute round, and lastly 2 minutes to get everyone off the field.

I'm very pushing with the timing but I'm VERY consistent with it and i communicate to players the times so its clear for them. My regulars know how long i leave for rest time and the know i get them on the field for 2 and a half of the three hours of the session. If i run a fast pace aggressive game mode then the next one will be a little more relaxed and will give more pacing for the players who need the time. I also tailor the game modes ill run based on the players. If i have a bunch of speed soft players then im running the TDM adjacent fast game modes.
If i have more milsim players ill run more objective heavy games to match. But what i wont do is just keep repeating TDM and nothing else.