If you, or anyone, can come up with an example of a company actually doing that, not just saying they want to, then I'd definitely reconsider.
I'm guessing that you're talking about Planetary Resources with the asteroid mining thing? I didn't see much about hard numbers from them, but I'm doubtful that they will ever spend tens of billions of dollars before getting a penny in revenue.
I can believe that private companies are good at making longer-term investment in technology that directly benefits a profitable line of business that they're in. Stuff like Intel doing research towards smaller component sizes on ICs. But who's going to invest long-term in fusion power? There's no company with a revenue stream related to it that I know of. The costs will probably break a hundred billions dollars before anybody gets plants on the grid that actually generate any revenue at all. I'm just not seeing it. If it were a realistic solution, why isn't it already happening?
(To be truly pessimistic...) Nor will NASA or any other governmental agency ever make use of asteroid resources. That'd be too useful. Instead they'll spend 400 years doing political stunts and in-space handshakes. In 400 years time, we'll all have uploaded ourselves into The Cloud and gone exploring simulated galaxies. The real moon will be empty, save for some smiley faces carved in it from Earth with lasers.
(To address the actual topic at hand, I think long-term research isn't getting done on either side.)
We'll see. The companies are being funded by people who have enough personal wealth to do it without having to answer to public company shareholders or directors; so they don't have to show revenue or profit the way a publicly traded company would.
Considering that there are private companies willing to invest in a project to mine asteroids, I think this is too pessimistic.
Also, you are implicitly assuming that governments are better at long time horizon projects than private companies. I've gotta disagree with that. A government's time horizon is the next election cycle. Yes, projects like MIT's fusion reactor can continue to be funded for decades, but in order to keep that funding coming, the people working on the project have to spend a significant amount of time every year or two convincing the government that the project is worth continuing to fund. We're only hearing about it now because they weren't able to do that this time around.
A private company that is willing to make a long time horizon investment is not going to have the same overhead required to keep the funding going, simply because there are fewer masters to answer to.