If anything I'm surprised that their valuation isn't higher.
I've been using Docker since early 2014 and they haven't gotten a dime from me. If you count the storage and bandwidth on the public registry I've cost them money.
Where does the money go.
What you described is a services/support company, something Red Hat has worked really really hard not to be over the years (to debatable degree of success). Being their for support vs OSS is not how you get great margins.
Anyway, at this level of the stack in prod settings brand won't take you that far.
That's simply not true. Having a support team they can call is, rightly or wrongly, a large part of the reason some companies consider buying Docker Enterprise Edition at all.