With all due respect to what I'm sure was a well meaning comment, I think your comment is also an example of why the problem IS hard. Lots of Americans think a vague prescription of "squeezing the richest a little more" is the answer to everything, including apparently declining R&D expenditures. It's not. More clean energy deployments and more social programs are not bad things but they also will not solve this problem.

If we want to fix this there are probably two broad levers that need to be pulled. Notably indiscriminately "squeezing the billionaires" isn't one of them because you want to encourage capital to invest in the US:

1) The US has developed a real problem with production quality/capability, it makes a lot of spam and trash, it increasingly can't make anything at home, etc. The two big trends driving this have been a reduction of competition in its domestic market (i.e. monopolies emerging) and a broad range of policies which encourage US companies to design stuff, license out and have the production done overseas by someone who promptly steals and copies it... hello China. What's needed here to actually make the US economy "great again" are strong enforcement of anti-trust laws and some kind of legal framework where the incentive is to not just design in the US but also build there. This certainly puts limits on what "the billionaires" can do but by no means is it really "squeezing" them or trying to limit what they can earn in the US. You want the capital to get deployed in America but under a legal framework that's aligned with productivity, innovation and job creation as well as profits. This is how you get private R&D going again. The US framework is more "scams and profits" at this point.

2) On the public side, the US formerly had amazing federal support for R&D. This sounds like it should be easy to fix but I don't really think it is. The government is not as healthy fiscally as it once was, and there used to be more public appetite for science and technology related expenditures; Americans seem more enamored with get rich quick schemes than with a STEM education these days. If you're a politician who is going to reward you for supporting big federal investment in long-term, moonshot R&D? Voters won't, the capital class won't. So personally I don't see much of a solution here without a cultural shift occurring first, we need to believe as a society that long term research and innovation can make a more perfect world, but due to the realities of the modern slopconomy we believe the exact opposite.

It's not stealing, it's learning. The original person still has it. Copied, duplicated, sure. But not stolen.