The state always had control of the currency - somebody has to (I suppose Bitcoin might be an example of a currency without external control but, on the other hand, the managers of Bitcoin are utilising block-chain processing and a complex algorithm to ensure proper management of it). When a state decides to use money instead of bartering, it must decide what the denominations are, what their value is, and how much is to be issued. So it must keep a grip on currency control, mustn't it? Similarly the free market does not mean a free-for-all, some regulations must be put in place to make a market eg weight standards so that everyone is using the some weight and volume measures.
Money arises on the market as a commodity valued by all, or almost all, voluntary traders that allows them to escapes the limitations of barter. Barter is abandoned by market-based decisions and not a political edict. Where you have chickens and eggs to offer me for my vegetables that you want but I want beef and you have none. If there is a commodity everyone values (like gold or silver) then I can accept that from you for my vegetables and use it to acquire the beef I want from someone else that values the commodity money.
Or course if a ruling state authority, under a wise ruler - there have been a few - accepts the market’s selection of commodity-based money, its authority can increase it uniformity and efficiency and expand that acceptance over a wider area and thus dramatically benefit the voluntary economy. But when a state organization tries to command what is money backlash is inevitable. Bitcoin today is just a market response to the fact that the legal tender currencies commanded by the political state are increasingly manipulated by political authority for political reasons and thus dysfunctional. The current American President is far from the only one – although he is the most blatant - that has sought to bend the Federal Reserve to his will for reasons of electability.
The rich in power did distort the free market by such practices as selling (to someone rich, obviously) the right of monopoly over the trade of some essential goods. In the UK, such practices were stopped in the 19th century, as the state became more democratic. The corn laws, which you mention, are an example of the rich dominating the state and using state power to feather their own nests - ultimately at the expense of the poor of course.
New capital is formed like everything else, work is done to produce it. Maybe those who do the work make capital should own it. Just a thought.
In closing I do want to point out that the non-state institutions of past were often not free of coercion. For example, the church, the employment guilds, and the institution of marriage were all in some degree coercive. And it was that coercion that helped to drive the social revolts against all of them. And there is little doubt in my mind that the idea of a democratic basis for the exercise of political authority that has, to a significant degree, replaced them was well-seasoned with the belief that the lower classes would benefit. And in certain brief periods they have – especially in culmination of the Enlightenment.
But how much of that benefit can be ascribed to the political state and how much to economic growth by social, not political, means is an open question. Certainly, current conditions in American cities and the populist political reactions many places reflect the fact that those gains have been reversing for a good while now and citizen-subjects are becoming radical even though democratic institutions have not (yet) been overthrown.
But economic growth has slowed and the blame (at least in America) must be laid at the feet of the political state. Looking back during the critical years of the aftermath of WWI and the economic aspects of the response to the Great Depression, journalist and classically liberal economic author Garet Garrett wrote:
There are those who still think they are holding the pass against a revolution that may be coming up the road. But they are gazing in the wrong direction. The revolution is behind them. It went by in the Night of Depression, singing songs to freedom…There are those who have never ceased to say very earnestly, "Something is going to happen to the American form of government if we don't watch out." These were the innocent disarmers. Their trust was in words. They had forgotten their Aristotle. More than 2,000 years ago he wrote of what can happen within the form, when "one thing takes the place of another, so that the ancient laws will remain, while the power will be in the hands of those who have brought about revolution in the state."
There has been a revolution in the state and the Enlightenment ideals and its associated political concepts have disappeared even though democracy is largely still operative. If democracy is not the problem, then the solution cannot lie there either.