Eliminating the cap on reported income for OASDI taxes while maintaining the current benefit structure would, in fact, generate substantial revenue because 50% of all reported income goes to people who are making well in excess of the limit of $147k. The goal in this case isn't to solve every fiscal problem, it's to stabilize a program that, over the last 80 odd years, most Americans depend on to a greater or lesser extent for support once they retire. There is no readily available or viable replacement and simply saying "Oooops, we have to reduce your benefits" isn't acceptable either morally or politically.