I agree in general with this sentiment. However, I think that "medical robot that can cure anything" isn't something you'd patent (as you'd have to make some of the details public). I imagine you'd keep it as a trade secret and only license the machine for use by your own technicians or something along those lines.

I do think that the key assumptions for this scenario are that companies become as powerful (if not more powerful) than countries, and the incentives change such that withholding medical care is beneficial to the wealthy.

Do I think this is the most likely outcome? No. But I think that current countries with partially starving populations are a "worst-case" scenario for what a society dealing with scarcity looks like.