Those are good points. As I think about it some more, it's not even just support that they sell (as in, you can call them up when there's a bug). The large enterprises they sell to value:

- support

- training

- ease of install

- ease of upgrade

- indemnity (e.g., Red Hat promises to pay your court costs if someone sues for patent infringement)

- stability (long term support releases)

Those are all things that plain old open source by itself doesn't provide, but Red Hat does.

Which are all things that usually no consumer pays for, hence the big failure of trying to sell FOSS desktop software.

business in the US has stopped paying for training, generally..