Libertatrian/Minarchist utopiae have existed, they were called the United States of America (1776-1861), West Germany (1948-1971), the Free State of Fiume (1920-1924), among others.

There are Próspera and Morazan right now which may or may not succeed.

Those libertarian countries all ended because of socialist takeovers failing to create socialist utopiae, even though they've consumed all the wealth the formerly free people there had accumulated.

The two Honduran free cities mentioned above are under constant attack by socialist governments so they might well die the same death.

So from my point of view, the important question is not: "How can we bring about an impossible utopia of free people?" but "The next time people become free, how can they defend themselves against those who would enslave them?"