Experience is also the key to your success. Because it is something that no school teaches. Many theories but not practice to learn experience is meaningless.
Yes you're correct, if you want to learn something you should study hard and always aim for your main objectives. And all of your hardworks will be paid off
At some point, many individuals has been more successful rather that being smart/intelligent in school, just like Bill Gates and many more who has proven that College Diploma is not the key to success it is the perseverance that we have and the ability of believing in yourself that you can.