It’s interesting to see the America's most prominent libertarian economist state that capital markets aren’t adequately funding risky business ventures...
David Friedman (anarcho-capitalist)'s comment on market failures is that they do happen, but what might be called government failures also happen, and are probably a worse problem.
"Individual actors usually receive most of the benefit and pay most of the cost of their actions, making market failure the exception, not the rule. On the political market individual actors—voters, politicians, lobbyists, judges, policemen—almost never bear much of the cost of their actions or receive much of the benefit. Hence market failure, the exception on the private market, is the rule on the political market."
This is an excellent point, and a place where libertarians and socialists have some agreement, that we have a wealth/power distribution that fails to encourage social innovation. I think the argument is mostly how it got this way, and how it should be addressed.
Socialists are concerned with giving more, and libertarians are concerned with taking less, but bureaucrats and plutarchs are aligned in taking more and giving less.