It has become fairly common for socialists to make statements like, "It's estimated that it would only take x billion dollars to end hunger or climate change."
This is always a dumb statement.
So, Marx's world view was teleological; he viewed all economic transitions, including capitalism, as inevitable and necessary. He thought that capitalism would create the wealth that could later be distributed evenly via socialism.
The problem is that that isn't how the world works. Even if giving a certain amount of billions of dollars to the impoverished world would feed everybody right now rather than just being stolen by rapacious governments, that's not sustainable. This is where the "teach a man to fish" lesson becomes clear.
Nations are poor because they aren't free. Dumping money into dictatorships is simply putting a bandaid on a severed artery.