I haven't played airsoft in a couple of years. Mostly because I don't have the time anymore. I used to play about once a month, but then I had to move to a different town, so now my preferred field is ~80 miles away.
If I'm using half a tank of gas just to go there and back, I want to make it an all-day thing. But I also travel for work nowadays, I'm only home most weekends. Taking my guns and gear on the road with me isn't really an option; space on my work truck is at a premium, and it wouldn't look good for me, if a DOT or customs agent were to stumble across an M60 machine gun during a level 1 truck inspection. I also have yet to find any airsoft fields that allow 18-wheeler parking. My truck couldn't physically fit on the driveway to my preferred field.
Spending a day playing airsoft means I've only got one other day, if that, to do my chores and run my errands for that week, to say nothing of how physically demanding the game is. If I push myself too hard while playing (something else that happens when I've only got a couple days at home per month), I end up needing the following day just to recover.
I'd pick it up again if I ever get a regular 9-5 job though, or at least something that gets me home every night.