From your experience how hard is it to become “something” in this world?

I say something in parentheses because everyone refers to it as very very successful. I recently graduated college and I just want to know some real life experiences. Ive met and seen some amazing people and incredibly hard workers but the they don’t seem happy and never fulfilled. I’d think from their work ethic they would be making tons of money but some of them make below average. It makes me feel feel a little hopeless