I would say one, max two.
On average.

I ‘ve added just a bit to the OP @rebbel.
And who are they by the way? I mean who are they (the ones you meantioned) to them?

Editors, publishers, spouse, god, skilled predecessors, someone from their past who may have saved their life, such as police officer, or organ donor.

Usually just one or two people that encouraged them when they were young, like a mentor at one of their first jobs.

@Patty_Melt I agree with your Editors, publishers, spouse, , skilled predecessors, since it’s strictly about their successful careers.
Life savers are huge for anyone for sure, without life there is nothing.

@zenvelo You mean like a job not related to their careers?

There is a reason why I’m asking. What is the number of the successful in their careers (real careers like the ones I mentioned) known worldwide living and dead? Let’s say Americans for this thread.

The famous thank the illiterati, the glitterati and imaginary beings so that’s a three plus the shoulders of giants.