Definite no. I can't believe anyone can argue otherwise.
If you want a player who did fulfil his potential, look at Cristiano Ronaldo. He did what it took to fulfil his potential by devoting his entire life to football and had all the external factors help him along the way. Here comes the list of things Ronaldo has going for him to ensure he became the best he could possibly be and that Rooney doesn't:
1) Hard and focused training to fully develop the body and relevant skills, like Ronaldo has done with his shooting and heading for example. Especially in terms of staying fit and lean, Rooney leaves a lot to be desired.
2) Eating and drinking correctly, like Ronaldo does by being a teetotaller and employing chefs to ensure his diet keeps his performance levels at a maximum. Rooney drinks. Rooney occasionally smokes. Rooney probably even likes a kebab or two for dinner.
3) Few injuries, especially during the crucial early years. Ronaldo has hardly had any, while Rooney's been blighted with a lot of injuries, especially to his feet and ankles.
Come to think of it, there are a lot of similarities in Zlatan and Ronaldo in terms of how they've worked to become what they are, even if Zlatan took a little longer than Ronaldo before he matured and started playing at the highest levels.
Either way, Rooney hasn't fulfilled his potential in the true sense of the word. He became very, very good at his best, but to become the best you can possibly be requires an almost unhealthy amount of dedication that Rooney just doesn't have. That being said, he probably got close in his early twenties. He was an absolute force back then.