I don’t know anyone who is well off by just luck, except an heir and heiress friend. They spent their teens and 20s living the van life (before it was a thing), bopping around sofa surfing following some guru or band, taping themselves to trees to prevent deforestation. My friend famously lived in a tree for like 8 months to prevent it being cut down! And then got married and went home to take over the family pile with its 20 bedrooms and 200 acres. That’s pure luck, though they have had to be pretty imaginative and ambitious to not burn the whole enterprise to the ground, literally and figuratively.
Otherwise, no I don’t think intelligence has much to do with it. It’s ambition and hard work. But a bit of financial support with education or business start up costs helps too.
I’m pretty smart (I have a PhD, always top of the class). In my industry, the most successful people are the ones who put in the most time to do the most work beyond the 9-5 and the ones with the jabbiest elbows. You have to be unnaturally productive, working evenings and weekends, my colleagues book in meetings when on holiday with their families, take work on the plane and shove their kids in front of an iPad. And you have to want to get ahead, get the next project, the next big payday, ruthlessly ambitious.
Dh is a totally different industry. It’s something creative that a lot of people do as a hobby. He’s turned it into a £1mil plus a year business, starting from scratch with like £1000 savings in our garden shed. He is smart, but not like brilliant smart. He’s 2:1 at an average uni smart. But he is really ambitious. Can plan for the future, see the bigger picture, is thinking now about things he will do next summer and how that will grow the business. He returns emails on a Sunday and on holiday and is always planning treats for staff and taking them away for the night for an event. It’s genuinely just working hard and never resting on his laurels. Things could always be bigger and better.