Note, Jesus does not equivocate seeing with possessing. You can look at every automobile that passes you, but no matter how hard or long you look at any car, that automobile, by your just looking at it, never becomes your own. Seeing is not equal to possessing. All this tells us is that the rebirth is the prerequisite to enter the kingdom of God. The ability to enter is not equal to having entered, just as the ability of a young man to become a doctor does not make him a doctor.
Further proof comes from the parables of the kingdom.
You have to buy it to get it, and it costs you everything. You have to pay nothing to get saved, but you have to pay everything in order to have the kingdom. I remind you of the Old Testament typology in this matter. It cost Israel nothing to get out of Egypt. Egypt represents slavery to sin.