Keynes vs MMT: which economic theory fits our world?

This gets MMT close to where it needs to be. Taxation, especially of high incomes, must be seen as a way to regulate the excesses of capitalist speculation - which often leads to dangerous investment products that the originators pump and dump, while the top 25% of households is left holding the bag - while the liquidity of the bottom 75% is severely damaged in the dislocations.

An Asset Value Added Tax, as a replacement for capital gains taxes, with marking to market at Option Exercise, IPO and first sale after inheritance, gift or donation - and with an expansion of the ESOP sales exclusion to all stock purchases - not just privately held firms - (a tax cut) - will unwind capitalism so that a more cooperative economy can develop - including worker control over consumption, finance, social services and housing - as well as retirement savings and CEO recruitment (open auction).

Until taxes are adequate - that is - until we take the money we would otherwise borrow - running deficits is actually essential for capitalism to be liquid. Since the 2018 Trump cuts - there has been too much liquidity leading to asset bubbles in crypto, housing, commercial property, consumer debt ownership, etc. 

When the crash happens, the best cure would be a doubling or tripling of the child tax credit, shifting  COLA bonuses to an equal dollar pay bump (not a percentage based on) and a higher minimum wage. Then, the pay bump will be enough for the median to keep up, low enough to end the salary pull on price levels - especially for housing and durable goods - that all goes toward the top 10%. The minimum wage needs to double, as well as an increase to the poorest retirees. A VAT scheme would then eat some of the excess price inflation that will happen when the working class gets lots more money.