All of the low hanging fruit that could be discovered by self-funded gentlemen scientists has been picked. That doesn't scale to a supercollider or a large RCT. Funding at the whims of rich benefactors is very susceptible to petty politics.

Politics is irreducible from human affairs, privatization doesn't eliminate politics. It relocates it to a different set of actors. That could be a better set, but when it is it's because it's a more local and hands on group of people, not because those people happen not to work for the government. Governments are awkward because they are deep bureaucracies, and deep bureaucracies divorce the decision makers from the impact of their decisions. Weaker feedback leads to worse decision making. Not because there is a magic property of government that makes it uniquely bad. Large corporations, universities, and other deep non-governmental bureaucracies have similar pathologies.

That's something of an exaggeration, they are empowered to do violence and collect taxes and other things that are more problematic when abused, but still, privatization isn't a silver bullet.