Everything can be "sold", especially in today's age with the new methods of discoverability. But I would argue scientists don't need to "sell" something in the capitalist sense. They need to link the hope of a new discovery to inventors, innovators and entrepreneurs. Sure, some things might "fail" to continue by failing to adjust to the markets, or some scientific discoveries might be used for bad things (ethically), but this is (1) both inevitable and (2) the responsibility of the scientists & the people buying the end product/service. If I'm not mistaken, most bad/evil/etc. discoveries were made by scientists working FOR the government/king/etc. throughout history. If anything, democratizing science through the capitalist markets seems like a more beneficial way to develop self-sustaining science. The key thing is transparency, which can be less present in the private sector, especially when corruption is involved(assuming transparency is demanded by the gov.).
How do you sell having lost $50M on research which ultimately went nowhere?
If you can't, then how do you guarantee that your research will always bear fruit?
The bottom line is: You have to be willing to fund MASSIVELY-expensive losses in addition to wins in order to make real progress. Scientists aren't magicians.
For every success there are countless failures which you don't hear about.