Would being smarter make us successful?
No, there is no guarantee that smarter people will succeed, because the reality of people no matter how clever you are, how wise you are in this life as long as you do not bring value to those people then they will not care.
Smart does not mean success, but using the intelligence that exists best will take you there. So look for something you like, you are expert, and bring value to others (paid people).
Depends, you can be smart and make it. But you can be not as intelligent and still make it depending on your work ethic.