On the other hand, that's harder to copy software, especially since many modern tools rely on having data. In addition to this, your sale can be reoccurring and you have a clear and more predictable revenue stream. This is a much safer business.
I'm not saying that things should be this way, but that's definitely the way that they are. Given that it makes sense to pay these people differently. If you resolved these issues I think it would be easier to argue for higher pay (not that they don't deserve it in the first place)
I think the problem in your logic is that you're treating it like a zero sum game. You're ranking these against one another instead of scoring them compared to a stable moral base. It is highly possible that software is protected adequately and hardware is not. This does not mean you need to bring the protection of software down to bring that of hardware up. This would be either zero sum or negative sum. But these things are not tightly coupled. We can absolutely just increase the protection of hardware while the protection of software is unmoving (or even increases).
And the thing is, as even absurd but amazing Minecraft examples have shown, software engineers can develop hardware, if inefficiently. True we don't know anything about 5nm lithography or whatever, but that's more a chemistry/physics/manufacturing domain.
Finally, even the hardware depends on software. It requires software internally to do its job, and the development of said hardware absolutely depends on software. Chances are, hardware engineers informed software engineers about their need for doing better hardware work, and the software engineers built better software to enable that.