Amazon reinvests all operating income from today to build the Amazon of the future.

SpaceX reinvests all operating income from today's offerings (launch vehicles) to build the SpaceX of the future.

Both companies appear to be bootstrapping towards a gargantuan vision that is likely decades away.

SpaceX basically has just one customer which it is entirely reliant upon. The government.

Amazon has millions.

> SpaceX basically has just one customer which it is entirely reliant upon.

As far as I can tell NASA accounts for less than half of SpaceX's business. According to their website they have nearly $5 billion in contracts and I can only find reference to just over $2 billion in NASA contracts.

> As far as I can tell NASA accounts for less than half of SpaceX's business.

NASA ⊂ "The Government"

SpaceX also has Defense (USAF) contracts. At least around $900 million already awarded (and that may not be all), and they recently sued to be allowed to compete for much more under the EELV program.

Good point, I hadn't realized the USAF contract was awarded to them yet. That puts government funding at significantly more than half of SpaceX's existing contracts. I still wouldn't say they basically have only one customer, but it's closer than I thought.

With the "technological moat" SpaceX is building, does it matter how few customers they have today if no one can compete with them?

Didn't a SpaceX competitor install second-hand 1960s Russian rocket engines in a launch vehicle that failed recently? Its not a fault on the engines - I'm sure they were excellent - but rather an anecdote on the gargantuan barrier to competition inventing new space technology offers SpaceX.