At one point, the American people fought for their freedom from what they considered an oppressive and tyrannical authority: the English Crown.
Some did. Some were merely opportunists who didn't want the government getting in their way. Most of the US founding fathers were smugglers and land speculators. They didn't like that the US had ended the French and Indian war by promising that in exchange for peace, their colony would stop expanding westwards. That pissed off the founders who had bought land to the west and wanted a return on their investments.
Other American people were just fine with the arrangement with the crown. They didn't want a brand new government, they thought things were fine as they were. These people were either killed or driven off their land by the rebels who wanted a new government, and were forced to head to England or up into Canada.
Just look at the other places that didn't consider the British monarch to be an oppressive tyrant: Canada, Australia, NZ, etc. Did they suffer under the grinding boot of the king and lead miserable lives as a result? Were they forced to hand all their wealth over to England? Hardly. Within a few decades the British gave their local governments more power. Now they all merely have the king as a figurehead and are fully controlled by the people.
Meanwhile, the rebel colonists in the US went only a couple of decades before descending into a civil war. Plus, there's the war of 1812 which, in large part, was due to these people who famously hated tyrants and oppression ignoring treaties and killing off natives so that they could expand westward.
It seems to me that if you look past all the propaganda that is part of the US school system, the British king being a "tyrant" was more of a convenient excuse rather than the actual legitimate reason for the rebellion.