With an increase in tariffs and taxes that the British Parliament refused to release from America, the colonists decided to instigate a war with the people that lived across the pond.
Between the Sugar Act that crippled the American economy in 1764, and the Stamp Act that further trampled down the American people the next year, the colonists were supremely fed up with the British Parliament.
By 1774, the Brits were contributing nothing to the American colony, but for some reason, they were asking for a consistent, and even massive at times, piece of the American pie.
This prevented the American people from being prosperous and independent from the European Union, despite literally being completely separated from the continent in and of itself.
The Americans wanted to fight back, so they began to revolt.
Great Britain felt like they were entitled to pass these arbitrary laws because of their involvement in the French and Indian War which ended in 1763.
The was was costly, and since it was fought in North America, this left Great Britain with a huge debt to the American people, which they felt was unnecessary to pay because technically they were of European ownership.
Most Americans disagreed. They thought that England fought the war strictly to expand their empire and build their wealth, not to benefit the American colonists, which they claimed was the case.
At the end of the day, the American people couldn't even vote in England, and they were still being held under British rule. It was only a matter of time before the tables turned.