UBNT how do they do it

Long time UBNT user, gear is great, support/software great, function is wonderful. How on earth do their books stay in the black. Their cost/function * longevity (its cheap and stuff lasts for looong time and is supported (software) for loong time) seems like their income would be constrained to say the least, but they seem to be crushing it.
THoughts?

The market is that big and ever growing.

Really very impressive! Maybe my brain has been warped by the support contract costs of the large enterprise vendors like Aruba, Meraki, etc etc