I agree with you. Working hard might sustain your daily living but it doesn't give you an assurance of having a sustainable life in the future. It's better to work smart where you are not just working for the present but also preparing for the future. There are lots of smart alternatives and one of them is investing.
Right, without intelligence you will never be able to generate wealth. I think working hard is not enough, many people work hard but only have a small income, they don't work smart. look at how Facebook, Microsoft, Apple developer and so on, they work smart, so they can become rich, innovate dude!
There are still some exceptions, many people don't have high intelligence but they can still be rich when they are heirs, money from their family is a huge number and it is enough to turn them into a wealthy person, and another case is someone who is super lucky, they can be successful or lucky in any job. But if we are not in special cases, we only have hard work, wealth cannot come as you say because this hard work cannot create huge and outstanding income, it's not enough, we need high intelligence to break that limit