Americans who owned property in Cuba before the Spanish-American War invested heavily to improve their holdings. They built railroads and factories to serve their own business needs. Their investments added value to the island for the benefit of everyone. Jobs were created. Productivity and exports were up. New products and services were arriving, and Cubans as well as island creoles were able to purchase them with money that they were earning from the Americans. After the war, American investment spread over the rest of the island.
Cuba had known such prosperity only once before in its history, during the few brief months that England had ruled the island after defeating the Spanish. Unfortunately, Britain traded the island back to the Spaniards in exchange for Florida, and Cuba returned to the economic doldrums. Spain never invested in the island or its people.
All that changed when the war ended and Cuba became an American protectorate. Granted, there were Americans who flooded the island. Their energy and industry overwhelmed the native islanders. Regardless of how much money they may have had, these Yankees were there to prosper and, as far as they were concerned, it didn't matter who had to get out of their way. The officials who had been sent by the United States government to administer the island didn't see anything wrong with this. Indeed, they likely hoped that the Cubans would learn the Puritanical work ethic from living and working with the Americans. Of course, Jose Marti's ghost must have recoiled in horror at the death of his beloved Cuban heritage.
However, just for the moment, let's consider what might have happened had America remained neutral and allowed Cuba to win its own independence.
Would the new government of Cuba have forced the Americans as well as the Spaniards to leave? It's highly unlikely. The Cubans needed investment capital to recover from the losses incurred during the revolution, and to begin building a modern country with a stable economy. Americans hardly would have been likely to pump more money into the island if they had been forced out. Furthermore, there was no other Latin American country with the means to help them at that time, and European nations couldn't be expected to help out a distant island that wasn't their own colony.
Would a free Cuba have been able to survive without outside investment? Possibly. However, they would have become another Haiti. That island struggled for centuries to survive let alone prosper. Indeed, it hasn't succeeded even yet. Of course, Haiti was saddled with the debt of purchasing itself and its people from the owners in France. That debt was only recently paid off.
Interestingly, a few months prior to the Spanish-American War, a group of American financiers crafted a plan for the Cubans to buy their independence from Spain using funds that would be loaned by the Americans. Had the Cubans availed themselves of this offer, they would have put themselves in the same position as the Haitians, and probably still be paying the debt.
It's fun to speculate, but it's hard enough to know what actually happened. Fathoming a history that never happened is not only more difficult, but also a meaningless intellectual exercise.