How did the american revolution become a world war

Other colonial powers like Spain, France, and the Netherlands got involved in order to adjust the balance of power with the British Empire.
Explanation:
At the time of the American Revolution, Britain had become the most powerful imperial nation in the world. In 1763, following the Seven Years War (which was, itself, a World War), the Treaty of Paris granted Britain much of the former French land in the Americas. As such, tension between France and Britain never really calmed.
Even at the start of the Revolutionary War, French, Spanish, and Dutch merchants had begun smuggling gunpowder into the United States through the Caribbean. Some estimates suggest that up to 90% of the gunpowder used by the Patriots came from these nations.
By 1778, France was concerned about the possibility of the British regaining their colonies and turning their full attention to fighting the French overseas. Following the Battle of Saratoga, in which the Patriots showed that their army was capable, France declared their alliance with the U.S. and send (mostly naval) military aid.
France's declaration sparked international declarations from elsewhere. Spain declared in 1779 that the time was right to recognize the U.S. and ally with them, and the Dutch joined in 1780. Both had been sending aid since 1776, and did not significantly change their involvement after announcing.
In India, meanwhile, the Mysore empire took the opportunity to push back against British imperialism, hoping to use French trading outposts as allied European power. The French, however, did not send the support promised.