One of the problems of determining beneficial effects is that in many cases there's no good way to count them. In economics you have concepts of 'externalities', 'unintended consequences' and 'alternative uses' - as in, for example, a local tax to fund the schools or build a bike path, etc. etc. The alternative use of that money per individual taxpayer could be used more beneficially (or not) by the taxpayer themselves. In 'campaigns' for the tax, sometimes it is described in order to minimize the effect - as 'one carton of cigarettes' or a '6 pack' or 'a few less trips to McDonalds, etc. ie any politically incorrect use. Where in reality, it may be putting away a few more bucks for college tuition, retirement, health care, vacation, etc. But those are not so easily counted.
The ban on DDT only became so evident by the renewed cases and deaths from malaria once the ban was in place (and when it was lifted by certain countries) - but prior to that - the advocates to ban DDT did not take those effects into consideration. In fact they totally dismissed them.
In my link above from the CDC - 2 more recent (within our generation) vaccines figured to save 13,000/year (an extrapolation from prior data and only AFTER the vaccines were distributed), but if you use the 450,000/year deaths from cigarette smoking and the percentages (if we had good data) of vapers who quit smoking and other factors of the less effects on certain body parts from vaping vs. smoking, then you could come up with an estimate of how many of those 450,000 deaths would decrease (or how many years longer a vaper would live) and it wouldn't take that much to overcome the 13,000 'saved' by vaccines.
