I think master's level degrees, including those in social work, actually are a good route for many people to pursue if their primary career goal is to be a therapist and see patients. The salaries in some cases might not be great, but I am guessing they can get to be much better than 40k/year in many situations and regions of the countries. Plus, you have way less of a life commitment/opportunity cost for pursuing a master's.
A lot of potential grad students see PhD programs as appealing based on prestige and having potential funding, which is understandable, but I think there are a lot of people pursuing this route who shouldn't be for various reasons (namely these two reasons, prestige and funding) if they are not super interested in research careers. It's created a huge backlog for applicants it seems, where really good potential applicants are now doing post-bacc positions for two years before even applying. When you think of the whole process of doing a post-bacc, a PhD, plus a postdoc, it's pretty insane what people are asked to do to make it in research-oriented careers. And the PhD system, although in some cases funded, still doesn't always end up being a super awesome route financially. There is a huge opportunity cost for making nothing but a graduate stipend that is at best barely liveable for 5-6 years, plus an often very costly short-term move and series of very expensive interviews for an internship system at the end of it all that greatly favors the wealthy/people who have family or partners who can support them.
So, I could see many cases where it would make a lot of sense for someone to go the master's route, even if that involves incurring a (reasonable) amount of debt for a shorter master's program that would allow you to make money sooner.
