In a 1992 article for the Harvard International Review, James Tobin wrote:
[The] idea that tax cuts would actually increase revenues turned out to deserve the ridicule [...][25]
The extreme promises of supply-side economics did not materialize. President Reagan argued that because of the effect depicted in the Laffer curve, the government could maintain expenditures, cut tax rates, and balance the budget. This was not the case. Government revenues fell sharply from levels that would have been realized without the tax cuts.
—Karl Case and Ray Fair, Principles of Economics (2007), p. 695[26]
Supply side proponents Trabandt and Uhlig argue that "static scoring overestimates the revenue loss for labor and capital tax cuts" and that "dynamic scoring" is a better predictor for the effects of tax cuts.[27]To address these criticisms, in 2003 the Congressional Budget Office conducted a dynamic scoring analysis of tax cuts advocated by supply advocates. Two of the nine models used in the study predicted a large improvement in the deficit over the next ten years resulting from tax cuts and the other seven models did not.[28]
I'm not talking about paying for themselves but they put people back to work. Trudeau's middle class tax break isn't paying for itself, infact it cost Canadians 1.2 billion dollars.