A lot of market forces tend to "naturally" create monopolies/oligopolies. For eg if you're the biggest steel plant you can operate efficiently and keep moderate margins, beating any plants not as big (economies of scale). An independent guy (or even the entire team) can't just open a new steel plant shop down the road, even if the current one sucks.
To be a bit honest, I'm a computational scientist who's never seen anything near 100K and likely never will. It's hard to imagine not having around 4 times my salary and not being able to start something myself.
I think your premise is significantly correct; things like launch HN (and even YC startups) are heavily software biased. I suspect you'll find about a hundred product hunt products for every physical kickstarter/indiegogo.
Even if you are good at those, for many companies, it's more about connections than about the ability to build stuff. So if you don't know the right people, it is very difficult to get a foothold.
Anyway in general, corporations are sticky. They save resources through scale and collaboration. Famously this is a problem for free market true believers because if you believe that the market is the most efficient mean of organizing people then you would expect firms to operate internally as free markets (or disappear). There is a whole body of work about it,
https://en.wikipedia.org/wiki/Theory_of_the_firm
In practice you can't just become your own boss and compete against firms.
Given I'm now in my mid-50s, things are looking grim. And I'm not getting paid SV silly money. I'm not even getting paid US dollers.