What is a "logistic success curve"?

A logistic curve is one which increases by multiplication. A logistic success curve is when the distance between different probabilities of success are measured in multiplication rather than addition.

Often one cannot improve an outcome by a fixed percentage, for example, adding 10% of the whole to a given probability moving it from 1% to 11%, rather one can only improve it relative to the current chance, for example making it ten times more likely. The problem is that for very small probabilities, ten times more likely is still extremely small. For such a case, if you start at an extremely low probability, than it is almost impossible to bring it up to a significant chance. since 10 times 0.000001 is only 0.00001 which still rounds to zero. For example, if something started out as a million to one odds against something happening, even making it a thousand times more likely gives you less then 1% chance of it happening