Success in the NBA and most Olympic sports is probably ruled out before you are born. For those for which it is not ruled out, they are a vanishingly small subset: good genes, born in stable country, family wealthy enough to afford training from a young age, parents who support/force the training. (I met an Olympic windsurfing candidate; he was tall, fit, relatively financially independent, born to a community near big lakes with friends enjoying the sport, and obsessed with the sport.)
Success financially (depending on what threshold you use) is largely ruled out by birth for most everyone ever born. Exceptions occur, and some places and time periods may have afforded the opportunity to more people, yet always a sliver.
So technically success isn't entirely determined before you're born. But for most it is at least off the table, unless the threshold is very low or they are exceptionally lucky and driven.
Success financially (depending on what threshold you use) is largely ruled out by birth for most everyone ever born. Exceptions occur, and some places and time periods may have afforded the opportunity to more people, yet always a sliver.
So technically success isn't entirely determined before you're born. But for most it is at least off the table, unless the threshold is very low or they are exceptionally lucky and driven.