Judge your success - not by the income it generates or the outcome of the work - but by whether or not you did "the things required" by the task at hand.
If you truly did "all you can" to achieve the goal you set for yourself, then you can hold your head high, no matter the outcome.
So are you successful?
The real question is: "Did you do all the you could to make it virtually impossible for you NOT to achieve the goal you set for yourself?"