Vonsalza:
The American Revolution succeeded primarily because of 1.) French support (a la “proxy war”) and 2.) the enormous logistical lag between England and the American colonies circa 1770. The advent of the jet engine pretty well counters #2 in favor of the government.
My impression is that it was multifactorial. Among other disadvantages the Brits had was the fact that the “frontier” was endless. People lived out in the hinterland than they didn’t know about and couldn’t control, but who could strike from their territories. Another was money. Parliament at the time was very money-conscious, and the American Revolution was a significant money loser from their standpoint, but without there being all that great a seeming reward at the end. The 13 colonies were not a treasure trove of gold, jewels and valuable spices like India.
Even if the Brits had “won”, they would have lost eventually, because they couldn’t devote enough soldiers or resources to keeping an ever-expanding frontier with an ever-growing population pacified. There was no end to it.