Since I know the founders of the first two: those are hardware companies. A non-trivial difference in everything said here is that when you need to put down an order to build and manufacture X000 units, other people in the supply chain aren't okay with "We'll just pay you per item as you make them on demand". To a degree that's what the "unless you're the next SpaceX" from the post seems to be trying to encode: unless you're in a structurally high-cost business, you better not need tons of capital.
