Apart from the Intolerable Acts, which were a harsh and unfair form of collective punishment, it’s hard to make the argument that the American colonists were much oppressed by the British government on the eve of the Revolution. There was a reasonable case for Parliament to tax them for their defense, they had their own assemblies, and for the most part, their rights as British subjects were respected. So why did they rebel?
For several reasons. First of all, many of them were the descendants of people who fled what they viewed as religious persecution in Great Britain. They consequently had no reason to love the mother country. Second, some of them weren’t even British by ancestry. Third, Britain might have kept a light footprint in the colonies, but that meant the mother country wasn’t doing much to help them. Most of the protection they needed from Indian attacks on a day-to-day basis they were providing themselves. Finally, and perhaps most importantly, it was clear that the British government was going to be an obstacle to progress in the long run, both through protectionist legislation and by preventing the colonists from moving west and taking Indian lands.
And so, in spite of the risks, a large majority of Americans supported the patriot cause. If that had not been the case, the Revolution probably would have failed.