Some points:

Businesses can become so big because capitalists that control the regulatory apparatus are able to use it to socialize diseconomies of scale, by redirecting the increasing costs of their inefficiency due to their size onto the taxpayer. That is, capitalists use government regulation to make themselves artificially grow that big.

Capitalists would only nationalize an industry of this size if they had squeezed out all ability to turn short term profits from having it operate in the private sector, but don't necessarily want to shutter the business like they would in the private market. They can then hang all the risk and losses associated with it on the shoulders of the taxpayer.

Conversely, capitalists will move to privatize an industry if they see the ability to make large privatized returns after having the taxpayer do most of the initial investment and R&D, like the space industry.

Crony capitalism is a redundant phrase. If you want free markets, capitalists will make sure you'll never get it, since capitalism is what happens to markets when the state intervenes in free markets on behalf of protecting the economic and social privilege of the capitalist ruling class.