Robots can only reduce costs of the production, but to earn any money corporations first need to be able to sell their products to someone, they need consumers. And you can't have starving, homeless consumers. You need to come up with some jobs so that majority of people still can earn money every month, so that you can sell them things regularly and finance all those fancy robots with a stable cash flow. Without that the whole economy as we know it would break. Not to mention that there would be a revolution or something long before that point. Transition, of course, will not be nice to many currently poor and unskilled workers, they'll be victims of the progress and this will continue for the few next generations for sure. But it's just a transition, jobs will eventually shift to something new, as they did before.