the policies congress enacts and the policy direction of congress and every other relevant body are dependent on the president.

To say he decided one day to champion a form of economics that is completely unfounded and unheard of seems unlikely to me.
sadly, that is what has happened. it is rare to find him support things that are economically sound. he couldn't pass econ 101.

note that the vast majority of people are illiterate on economics. it's so bad that economists often say one of the worst things they have to deal with is illiterate yet confident opinions on economics. this point can be understood just by knowing that econ 101 teaches the minimum wage reduces total surplus, yet many millions of people think it's a good idea. as well as we know that gravity makes apples fall from trees, we know that the minimum wage is bad economic policy, yet an entire political party and half the voting electorate supports it.

populism can be quite dangerous. sanders is an example of it, as is trump.