Can he turn Apple into a computer company that would focus on replaceable, modular electronics? Something like Fairphone, but on a bigger scale and with more resources, or that could have more runway without turning a profit? No, he can't. Apple is known for being a company that wants to integrate everything and needs to control all of its process. And for all the environmental talk, they would never sacrifice their bottom line to ensure their products are really green.

Could he turn Apple into an online education platform that leverage open source platforms and open hardware to make it as affordable as possible to everyone? No, he can't. Apple depends on the brand of exclusivity and premium products.

Need I go on?

When did Tim Cook become interested in those things? No he can’t turn Apple into a pizza delivery service either. And?

Apple is a hardware company that makes phones, pushes for a "green and socio-environmentally fair" agenda and also markets its computers to young people and the education market. Is it really that much of a stretch that this someone at Apple would be interested in working on these areas?

In any case, it's a sad state of the world when even the CEO of the richest corporation in the world can not be allowed to be interested in anything else that is perfectly aligned with the company's goals.

Wouldn't he have done that by investing some of his money by now? It's clear he's not interested in those things and his interests align with Apple's

More likely, he can not invest in these kind of things without being called out for conflict of interest.

But anyway, you asked if there is any kind of job that he couldn't do at Apple. I just gave you a couple of examples. You didn't specify that it had to me something that he would be personally interested in doing publicly. I don't know him personally nor I care about him (or Apple) to spend more time and thought about the matter.

If he did, would he then be worth the 750 million?

If he did, it would be because the board would have approved the decision and would be willing to make this kind of bet.

But this is getting so much in the realm of the hypotheticals, I really don't care about the argument either way.