The root of confusion was in the OAT "principles of flight". There is stated that "0.5 x rho x V^2 = dynamic pressure (IAS)".
It is absolutely true that 0.5 x rho x V^2 = dynamic pressure.
Hence I thought that dynamic pressure is the same as indicated airspeed.
But it is not true that 0.5 x rho x V^2 = IAS.
The ASI is nothing more than a differential pressure gauge. It measures the dynamic pressure and gives an airspeed indication that is proportional to that dynamic pressure.
But because dynamic pressure = 0.5 x rho x
V^2, the relationship is not a linear one.
If we double the airspeed we get 4 time the dynamic pressure.
If we triple the airspeed we get nine times the dynamic pressure.
If we quadruple the airspeed we get 16 times the dynamic pressure.
But in these situations we do not want to see the speed indications increase by factors of 4, 9 and 16.
To prevent this the mechanism in the ASI carries out a process called "square law compensation" This takes out the squaring effect, so that the indication increases at the same rate as the airspeed.