You'll have to figure out the prosperity part yourself, but it is my contention that living long (as long as you can manage) is useful because it takes about forty years to figure out what happened in the first thirty years, even if you paid close attention. Longer if not. This is a philosophical question, or a psychological question, or perhaps a gerontological question. It occurs to me that I can figure out things about my life and life at large that once mystified me, even as events in the present may mystify me. Agree, disagree, or elaborate as you will.