Success is accomplishing the thing that you want to accomplish. To most of the human race, success is strictly related to money. And so i wonder - what did Einstein mean when he said "not to become a man of success"? Do not become a rich man? I think so, yes.
Being a man of value is a hard thing. It's complicated to make people think about you as a valuable man - but it's harder to be a successful unvaluable person.
It's always hard to make things right - but it is easier that leaving them as wrong as you made them by a mistake. It's hard to face your conscience. It's the hardest thing on earth.
It's easier to be poor and honest, and loved by the other - "a man of value" - than a man rich, envied, abandoned "successful man".