A person can be prosperous one day and ruined the next, without making any change in his mood, character, or actions.
Furthermore, people who use different methods might achieve the same results, and people who use the same methods might achieve differing results
Why?
Well, aside from chance and individuality, it is a matter of whether or not people's actions conform to the spirit of the times.
Though someone's actions might succeed under a certain set of circumstances, these circumstances might change-and thus, the requirements for attaining successful results might change accordingly.
But people often lack the prudence to really know how to adapt themselves to change in most of their activities, and instead usually commit themselves to one or a few methods they have frequently prospered with in the past. *