It is absolutely possible to create the illusion of having your real hair to the extent that no one could really tell just by looking at you.

Nonetheless, different people have different levels of success in creating the illusion due to (mainly) trying to do too much on their own without help from a good stylist (at least at the beginning) and, let's face it--- different people have different ability levels when it comes to working with their hair (real or otherwise). Also, like Xeon wrote- time and experience really helps a lot.