I think the real question should be: Why don't more people dig personal tunnels? It's pretty obvious that digging is an intrinsically satisfying activity. Kids are naturally drawn to digging and we see unmotivated digging behaviour in the animal s all the time.
Most of us lose the digging instinct as we graduate into adulthood the same way we lose the drawing instinct or the the sculpting instinct. But, as adults, we do plenty of menial, repetitive tasks as hobbies. Knitting, chopping wood, doodling, spinning pens etc.
I think just not enough people have been exposed to the joys of digging as an adult and thus, have not been converted to digging as a hobby. I'm sure, if it reached some kind of critical tipping point, personal digging would become a mainstream hobby in the same way knitting & crochet did for young women in the 00s.
I stopped enjoying physically moving large amounts of dirt in my late teens, after years of being free labor for my parents' landscaping efforts.
I still enjoy tunneling underground, making neat passageways, modifying the world, and finding things. It's my greatest pleasure to play on my Minecraft server. This is where I do my digging, tunneling, and many other things.
Your comment makes me think of the tens of thousands of people who pay thousands of dollars to spend a week every year working as amateur porters, builders, truckers, riggers, cooks, mechanics, and cleaners, sweating away in extremely hot, dry, dusty desert conditions. I refer of course to Burning Man.
I don't like digging or being put into a tunnel, I like the free space and the wind, sorry, no digging for me. So a reason why more people don't dig is that some people just don't like it. At least me?
Most of us lose the digging instinct as we graduate into adulthood the same way we lose the drawing instinct or the the sculpting instinct. But, as adults, we do plenty of menial, repetitive tasks as hobbies. Knitting, chopping wood, doodling, spinning pens etc.
I think just not enough people have been exposed to the joys of digging as an adult and thus, have not been converted to digging as a hobby. I'm sure, if it reached some kind of critical tipping point, personal digging would become a mainstream hobby in the same way knitting & crochet did for young women in the 00s.