Neoliberal beancounters. If you repress the population you will need much larger government expenditure which both increases inefficiency and drives up wages among the remaining labor force.
Yeah except with the advent of automated systems and AI, human labor is quickly becoming less and less important... I'm sure you've heard of what Ray Kurzweil refers to as the Singularity -- its the point where technological advancement is taken over by AI and becomes to rapid for humans to comprehend. It will happen, we are close. Skilled labor will become meaningless. So that point of yours is moot.
Why would the ruling parties that be take any steps towards undermining their profits?
Firstly, things aren't always about profits. Many of the people running the show (i.e. the ruling class) are far beyond worrying about profit anymore. I come from a rich family (like a good bit above the 1%), I know some even richer families -- families with names that you'd recognize, people who are literally members of the CFR, Bilderbergers, etc . Guess what, they're not in it for profit any more. They care about what they perceive to be the best course for Earth and Mankind as a whole. But heres the thing, they don't care about you, and they don't like poor people. I live in TX, and one of my better friends is the son of one of these people. I go out to his ranch quite often, trust me, the whole "there are two many people that add nothing to mankind" thing is real. This kid legit would kill a large portion of the population if he could do it with no consequences.
The truth is, historically, ruling powers and the elite have never had the people's interests at heart. Time and time again throughout history we have seen rulers do terrible things to their own people. The idea that we as a culture are immune from this is absurd. You may not like guns, and thats cool. But as history has also proven, prohibition has never been better for society (EVER). It didn't work with alcohol, it doesn't work with drugs, it definitely won't work with +300,000,000 firearms.
Though you've likely heard this argument before, I will parrot it. We don't have a gun problem we have a mental health problem. The idea that making guns harder to get will fix this won't work and it distracts people from the real issue (i.e. how 80% of these sickos are on some kind of drugs, while the rest are usually radicals of some sort).