Most of my generally very pro-market older relatives are actually kind of squeamish about that sort of thing, oddly enough. They're probably more libertarian on government and regulation than most younger people I know, but much stronger on a "fair price for fair work" sort of ethic, where they look down on arbitrage-type plays, and on charging too high markup above cost + moderate profit. To them, running an "honest business" that charges reasonable prices, based on hard work, and doesn't engage in any trickery, is what American capitalism is supposed to be about (in a mid-20th-century white American middle-class view of capitalism).

My parents are very much left wing but have no problem with arbitrage (unless you rely on people's lack of knowledge or on their stupidity to pull it off) or charging market prices.

Don't ever regret that.