Privatized ATC would have an incentive to run a safe operation. If a mid air collision occurred as a direct result of an incompetent controller, confidence in the safety of the system would be eroded, people would stop flying, and profits would fall drastically. There is a profit motive for all the airlines to keep the skies safe and efficient and that would involve hiring competent people and retaining them for an entire career as high turnover, especially in a job that takes multiple years to train new hires, is extremely costly. To hire competent people, you need to pay a wage that entices them to work in this career field. Otherwise, they'd just work in a field that pays well enough for a high quality of life. If people are competent, ATC won't be their only employment opportunity.
Contract towers can pay what they do because that's what the laws of supply and demand dictate they can pay still attract enough qualified people that can staff the tower. I'm honestly surprised they can get people to work in these towers in bumfuck nowhere, and a lot times they can't. But to the extent they do, many contract tower employees are either too old to work in the FAA or they are younger people with experience using it as a stop gap while they wait to get into the FAA. There aren't enough people willing to do the job for contract tower pay and benefits to staff every tower, approach, and center. I tell people about this job and the current pay and benefits aren't enough to entice my friends with career aspirations to even apply.
And yes, while I generally believe that taxation, especially income tax, is theft, the subject was subsidies. It is morally wrong for the government to take money from me or anyone else and give it certain industries to offset their business costs. Centrally planned economies don't work. If there is a demand for something, the free market can and will balance out the price with supply. Here's another example of government subsidies gone wrong: The National Flood Insurance program. Long story short, the government subsidizes flood insurance for people who are typically well off (like people who own waterfront property in the Florida Keys) but don't want to pay the exorbitant premiums it would cost for an insurance company to write a flood insurance policy. Obviously the insurance company would be taking a big risk should a hurricane roll through town and a storm surge cause billions of dollars in damage to an entire town, much like Fort Myers recently. Because the insurance is subsidized, it is affordable to more people than it ordinarily would be in a free market and in turn, it encourages more people to build in flood/hurricane prone areas like near the beach.
Tl;dr No, I don't support the government taking money out of my pocket and giving it to well off people to buy a new Tesla and repair their beachfront house that continually floods