Even if the actual monetary cost is paid for through an internship, the opportunity cost is still monumentally high. You're still paying for it mightily in terms of one less year spent collecting an actual salary or pursuing your dreams.
Now, if you'll be miserable doing what you studied for several decades, then yeah the equation is a bit different. But most people are fairly burned out by the end of a normal 4-year college, to say nothing of adding a master's degree on top of that and this might be the feeling you're experiencing.
In an ideal world, you could probably take a few months off and pursue something fun or travel and refresh yourself mentally. I bet you'll approach your current field with a renewed sense of passion and be able to evaluate what you want to do then much better with a little break.
