If you are an activist protesting against the high costs of living, we would like to offer you one suggestion: do not demand that the government reduce consumption tax. Social activists tend to believe that a government policy reducing consumption tax can, by itself, benefit the general population. This paper explains our suggestion to the contrary. The tax field alone is insufficient for consumption tax reduction to be effective in increasing consumer wealth over benefiting suppliers. Due to cognitive biases, or heuristics, when the government changes consumption tax rates in order to increase consumers’ well-being, suppliers are able to fix market prices above the normal equilibrium prices; this is especially true with low-priced and nece...