If smart and motivated teams can't do something, can anyone?
With something like soil, maybe they figure the technology will be useful even if it only services projects with easy terrain and environments and avoids areas with swamps.
Actually, the story is that Musk made it up on a whim while stuck in L.A. traffic, founded the company the same day and bought a used drilling rig which started digging in the Tesla parking lot.
Really the main difference is that someone without money and follow through would've just sat in traffic and complained.
Yes, of course, now that he has money, connections, and a powerful reputation, that makes it easier for him to do things. But he created the money, connections, and power by being able to do things even when he had none of them.
And in general - entrepreneur "origin" stories are often bullshit - useful to get go PR, that's it.
You might want to look at them closer. Hyperloop and ET3 are very different from a technical perspective, even though they're superficially similar.
ET3 tubes need 1/1,000,000th of an atmosphere to mitigate the sonic boom, and that makes the pumping requirements exceedingly hard (requiring multi-stage pumping with turbo- and cryo-pumps). That also means ET3 has a higher top speed, assuming you can secure the right-of-way to satisfy the minimum curve radius.
Hyperloop tubes use 1/1,000th of an atmosphere, chosen because it's the lowest pressure achievable with purely mechanical pumping. They then route air around the pod, allowing them to approach the speed of sound despite the fact that air has to speed up as it squeezes around the pod (aka the https://en.wikipedia.org/wiki/Kantrowitz_Limit).
So ET3's pumps see basically the same differential pressure, but 1,000x more volume needs to be pumped per m^3 of air that leaks in. This means the Hyperloop requires less pumping power, fewer pump units, uses only cheap mechanical pumps, and can tolerate more air leakage than ET3. This is a big win, since the tube is the expensive part.
let's judge the outcome - or lack of it - when they fold or succeed.
Cities of 500000 inhabitants which have a subway exist. See
My family is from Lausanne and I spent a few months studying in Rennes–the size and density plus the metro system makes these cities really pleasingly 'human scaled' in my view. Walking-first center city areas with lots of restaurants/shops, easily accessed from less dense areas by metro+good bus systems+intercity train, but small enough overall to not feel sprawling.
But what if the cost were a tenth as much? I posit that for a city of 500,000 - 1,000,000 it might become practical to have subways and that radically changes the transit equation.
So I am very bullish on Musk bringing down the cost of tunneling. It all depends on how low he's able to reduce the cost.