It seems to me that wishing for an ancap society is like wishing for a society that is crime free. Since people have their own wills and agendas, we will probably never have an ancap society for the same reasons that we will never have a society free of all crime.

But that doesn't matter. Working to have a society that is free of crime is a noble, worthy, and productive goal and activity even if we never achieve it, and the same is true with an ancap society.

Also, being ancap has lots of benefits even if we never fully get there. One for me was my ancap understanding that copyrights were a fake and immoral property right, that lead me in the direction of open source software, and had a very positive role in my career. Another, is ancap wisdom has caused me to avoid US treasuries as an investment, and to be attracted to technologies like crypto currencies, which has also had a very positive outcome for me. Also, I avoided getting killed with the housing bubble (austrian economics) that crushed many of my friends. Another one was taking my kids out of government schools, and educating them myself. Their education isn't perfect, but they avoided a lot of the problems their friends and peers did.

Anyhow, the point that ancap is a valuable goal, even if we never do reach the perfect ancap destination.