All the examples you provide involve money. So for you "doing something big" is about making it financially. I guess all the hippy stuff about "leaving a world better than the one you found", "making a contribution", etc, would just be a bonus for you (everybody, when reminded, adds "yeah yeah, that too", because makes you sound sensitive). That's a first hint about your interests and priorities in life. Now how to court money? Ah, I wish I knew myself. There is something about money that makes it like a completely different realm. Some of the members of our species get it and some don't. And usually, if you look at economically successful people, they are not the most intelligent or cultivated specimens among us.
But then, one day they will die, like any other of us. We all die alone. In your dying bed, will you look at your safe full of gold and say "it was worth it"? Or will you need something else to bring you peace? Because that's what vocation means. What will bring you peace at that moment, when the picture is complete? Keeping your mortality frequently in mind is not depressing, on the contrary it helps you living a better life.
And oh boy, how easy is to solve other people's life instead of looking at your own mess. But you asked for an elaborated answer so there you go.