The measure of success or failure is always a function of time. How long do you wait to consider the outcome? 

For a short goal you want to wait for 5 years to see how things will be. After year 1 things are worse off yet you want to complete the 5 year cycle to determine the success. Even after 4 years you wan to wait it out till end of year 5 only to see that it was a total failure.

Do you want to wait 100 years when last 15 years have been utter failure?

When the 15 years started people had hope for a better future. Hope of a better future was pedalled and now 15 years later, you want to pedal them hope that thing *might* be better in 85 years. After 15 years things will probably deteriorate more and you will say in 60 years and it will go on till it's year 100 and you will not be there anymore, but the hope you pedalled will have left a lasting irreversible  negative impact.

You can compare it to HIV infected patient. There is a medicine to maintain the patient's health to make him survive longest by taking the survival pill. They just don't have the cure pill. Let's say you want to experiment with a supposedly 'cure' pill and start giving the cure pill instead of survival pill. After year 1, the patient's health deteriorates but you say it will take time. How long are you going to give hope and wait to see if the pill cures the patient, when it is highly possible that it will end up killing him.

I would rather give him the surival pill so that at least he can lead a longer life.