they make tunnels and outfit them for various modes of transportation. it's not a joke. i can't imagine any better way to make it clear that something isn't a joke than to put $100 million into it.

Is $100m really enough to build a state of the art boring machine and get all equipment/labour to actually build a tunnel?

That's just shy of the cost of building (drilling?) the longest road tunnel in the world, in Norway, which has really high labour costs. So I'd guess it goes a long way (pun intended).

https://en.wikipedia.org/wiki/Lærdal_Tunnel

Enough to get started and enough to get more money eventually. Its a market, lets see how it gone go.

Really? Care to give some examples?

Yes, SpaceX and Tesla.

You said words, but there's no substance, how does SpaceX and Tesla in any way prove that "Elon Musk gets more done per dollar than anyone else alive" exactly?

Well, they take dirt and turn it in to a big, long, nothing. AKA a tunnel.