Although you raise a valid point, it overlooks the role that the actual games themselves play in deciding the outcome of a generation. A higher userbase attracts support from developers which means more games for consumers. IMO software is also a important indicator of success which profit from hardware sales has absolutely nothing to do with.
But yes, if you only take profits into consideration, then Nintendo beat the PS2 last generation. Of course, big, diversified companies like Sony and Microsoft are able to absorb such heavy losses.