You are 100% right. I completely agree that people should work smart everytime. Life is unfair and there is no way to refute that, that's why we all need to find a strategy or if not a loophole in the system to make our place in life a notch higher. One must use brains and adapt depending on the environment and factors around him or her. Sometimes even those with fewer resources came up to rise as they know how to play their cards and not just take life as a shotgun shot. Work smart and play hard and no drama, that's what I follow in work.
I really liked the way you put it: work smart and play hard. I also massively agree with your other point regarding people who may have fewer resources (brains, industry, dedication, propensity, whatever that might mean) but who still manage to rise higher in life simply because they know how to play their cards.
I do not agree that working hard or working smart can bring financial success but I think financial success is a function of meeting the right people and having access to the right information.
If you are not smart, then meeting the right people and having access to the right information won't help you much. The right people are smart themselves (well, for the most part), so they will quickly find out that you are not worth their attention (and money). If you are as dumb as a box of rocks, you won't be able to use the information you obtain to your advantage. And it is unlikely that you will have this information in the first place, if only entirely by chance.
Although, who needs brains if he has luck at his side?