School grades have no impact on being successful or not. At all. While it looks nice to have A's and it adds to your portfolio, people in the real world arent dumb anymore. They hire whats experienced, not whats awarded. A dumb person who never completes high school but goes long enough to learn how to learn and communicate can be successful. Thats all schooling proves, you learned how to learn/adapt and learned how to communicate to others.
Monetary wise, the smarter a person is the higher the chances they can make more money. Thats because a dumb person can only do manual labor jobs and can only work so much a week. A smart person can have tons of businesses, investments, and operations going at the sametime. Just because you write and earn anything at all on Hubpages means your already becoming smart. Serious money doesn't come from the efforts of one income source and one job, it comes from 24/7 income sources and many efforts.
Dumb - Landscape worker: works 55 hours a week at $14 an hour. $770 a week gross.
Smart - Full Time McDonalds Worker: 40 Hours a week at $8.25 an hour. $330 Gross. Also has 10 Websites that Make $30 a Week, $300 a week.
Does ink cartridge refills on sundays for 3 small businesses $250 a week.
Has $880 a week gross income.
The landscaper doesn't have the skills to make other income sources, and because of it has to work 15 more hard body intensive hours to make close to what the relatively laid back McDonalds worker with a degree and smart work ethic makes.
Im not saying landscapers have to be dumb, or McDonalds workers are smart - im just saying thats how the different people would play out. The real world overlaps so much more then examples or questions like this can be answered. For all I know the landscaper saw a house to buy across from a job one day, bought it, is renting it to college students and making $2,300 profit a month on top of the maintenance, utilities, and morgage and continues doing what he enjoys - landscaping.