They think it's a necessary cost of avoiding government oppression. They have some delusion that they're somehow mutually exclusive. They never consider: ¿Porque no los dos?
Depends on the person and the type. I've never met a libertarian that didn't at least pay lip service to regulatory capture and corporate rent seeking. They just don't follow those base ideas to the end point much of the time.
They often enough blame these problems on the state. Like we aren't capitalisming hard enough and if only the last remnants of regulation will fall, the shining light of free market economy will make everyone happier.
They fundamentally think that state power is (to varying extents) unethical. They also think human interaction should be voluntary (for the |ost part). It's awkward to think that people deserve to live and trade without interference and not think a group of people should be able to if they want.
Lots of people conflate capitalism, voluntary interaction, and whatever the fuck we have going on now. I won't get started on how fucked most people's view of (proper) left ideologies are.
So we line up, use proprietary language, and throw rocks at each other while shouting absurdly reductionist slogans.
David Graeber's book "Debt: The First 5,000 Years" really opened my eyes to the huge variety of economic systems that have existed. There's so many other ways we could be living.