The seeds that fell among the thorn bushes are also people who hear the message. But they start worrying about the needs of this life and are fooled by the desire to get rich. So the message gets choked out, and they never produce anything.
Later, as Jesus was sitting on the Mount of Olives, his disciples came to him in private and asked, “When will this happen? What will be the sign of your coming and of the end of the world?”
If he had offered himself every year, he would have suffered many times since the creation of the world. But instead, near the end of time he offered himself once and for all, so that he could be a sacrifice that does away with sin.