It's a bold and perhaps unauthodox claim to make.
Success is really the progressive realisation of worthwhile pre-determined goals.
It is this very journey which makes or breaks us. As we all make mistakes it makes great sense to learn from these and look for other possible ways to resolve our situation. It was probably hard to get employed directly into the job you wanted as the employer wanted those who had experience to work for them. As we error and learn from our mistakes we tend to react accordingly making us a little more aware of what needs to be done in order to achieve our objectives. If we had succeeded immediately without tasting the disappointment associated with failure then it's possible that we may not have not been so adventurous in looking for other possibilities such as that outlined in the first point.