The most accurate reason for why the French supported the Americans during the Revolutionary War is that the French were angry with Britain and wanted to support its enemies. After suffering defeats against Britain in previous conflicts, including the Seven Years' War, France saw an opportunity to weaken Britain by supporting the American colonies in their fight for independence. This support was motivated by a desire to avenge past grievances, restore French prestige, and diminish British power in North America.
While there may have been some belief that supporting the Americans could lead to economic benefits, the primary motivation was indeed the animosity toward Britain. The notion of fearing an American attack or wanting to reclaim land was not the main impetus behind French support in this conflict.