Why is it in this "great country", if you take Social Security at 62 you can only earn $12,000 per year?

No, "very rich people" would not participate in Social Security if given the choice. If the "very rich" wrote the laws there would be no Social Security. A rich person that retires will be lucky to get back his original investment in SS while the lower-level worker gets his money back in just a few years. Facts are stubborn things.