The short answer is because they better. Unfortunatly when it comes to products of this nature you really do get what you pay for. As a distributor of these products I can tell you that everyone who has tried my double x nutritional supplements which are also made by nutrilite loves them and continues to use them.
I don't really know why the person you bought them from said that they were the "only real vitamins" we all know this is not true. Also there claim to be #1 one in the world is true, but this is based on sales. They out sell the #2 by 10 times. Also all our my products are backed by a money backed guarantee so you can try them without risk.