the boring company is basically half joke, half crazy idea and even musk admits it, just read an interview piece where he shows a TBM to a reporter. he doesn't come off as completely serious about it. if it works out, though... we're talking big business.
Tunnels will be important on Mars.
Why?
In my book, tunnels, road construction, mining, oil & gas are quintessential examples of diehard reactionary industries making snail pace progress, with entrenched corruption and basically insurmountable barriers to entry.