Two very good and short articles about marginalism -- and how people ignore it's importance.
The first -- Marginalism - Econlib -- discusses the concept generally. How people confuse "Total Utility" with "Marginal Utility", and the enormous costs of that misunderstanding.
The second-- Maximum Vaccination - by eugyppius - eugyppius (substack.com) - focusses on how so many resources are being spent on trying to vaccinate a high percentage of the population, which will has very little effect on the per capita cases of Covid. The chart below summarizes low correlation between population vaccination rates and Covid.















