The downside is that the public will spend 10s of billions only for some billionaire "startup" to hire away the physics expertise and the public ends up paying

The downside is that the public will spend 10s of billions only for some billionaire "startup" to hire away the physics expertise and the public ends up paying a monopolistic/oligopolistic premium. Now theres nothing new about that.. but when talking about throwing tons of public money at something it's important to control the terms on which the public money is spent and who absorbs the risks/rewards.