But to understand causation better, it can help to examine places that adopted major libertarian economic policy changes, and look at their performance before and after the shift.
New Zealand in 1984 underwent perhaps the largest shift ever towards libertarianism, called The New Zealand Experiment. What happened shortly after that is they had almost zero growth for the next 6 years, and they fell from having the 4th highest GDP per capita to having the 15th. Poverty increased, foreign debt skyrocketed, and income disparities rose. Between 1985 and 1992, developed economies grew by an average of 20%, while New Zealand's economy shrank by 1% over the same period.
They started to recover some in the 90s, and in 1999, the libertarian experiment officially ended when the new Labour/Alliance Government was elected.