I dont see how having somebody else pay off your mortgage in full could ever be considered 'too little gain'. If house prices came down, more people would be likely to buy 2nd and 3rd homes and fill them with tenants.
Moving isnt an option for everybody, some people cant leave their family for various reasons, but you can always try to better your earning capacity. Sacrifice is required unfortunately, we all have to do it, some are lucky, but the rest of us only have the choice of which part of our lives we make it, if you avoid it whilst young, you will make it whilst old and vice versa.