Why did expansionists set their sights on the annexation of spanish cuba?

Many expansionists believed that the Haitian Revolution could repeat itself in Cuba, leading to the overthrow of slavery on the island and the creation of an independent black republic. Americans feared that the British would seize Cuba, which would render all slaves on the island free because Britain had already outlawed slavery.

Explanation: Hope this helps :)

the population grew a lot and was making more money

the us constitution is a living document, meaning that it can be changed over time as the country changes.