There’s always going to be a huge market for good designers. The key word is good. Not only do people love saying “my designer did this” but also commercial buildings rely heavily on designers. If you do it right there is no reason not to make a bundle. You make money by; your hourly rate, selling items(retailing) subcontracting out jobs to painters, electricians, carpenters etc. You act as a general contractor. Go to school, get a job working for a designer and you will see how they live.