First of all, inflation and hyperinflation are two really different things. The first one being common in history while the second one is rare but catastrophic.
Then, In Friedman's book inflation is related to the amount of money in circulation, yet since the 80s the amount of money and inflation have almost zero correlation in the US. Some of Friedman's concepts were useful to reach that point, but still: we now have been living for 40 years in a world where Friedman's model is unable to explain anything.
Then, In Friedman's book inflation is related to the amount of money in circulation, yet since the 80s the amount of money and inflation have almost zero correlation in the US. Some of Friedman's concepts were useful to reach that point, but still: we now have been living for 40 years in a world where Friedman's model is unable to explain anything.