That stopped being true 70 years ago, and it was the withdrawal of American aid that brought Castro to power (he still pretended to care about human rights then).
"Aid" is a bit of an understatement considering that Castro was fighting against the US-and mafia-backed dictator (Fulgencio Batista). The withdrawal of American support to Batista happened because the corruption and violence had reached unsustainable levels even for an anti-communist.
People make this argument - but itβs consistent through history with moderates as well as non-moderate government. Withdrawing support is always seen as weakness an established state and leads radicals to overthrow governments. Germany 1931(bankers withdrew funds), Afghanistan, Cuba, Vietnam.