Well, I didn't go to film school. I didn't make my first film until I was 43. I am a the position where time is more valuable to me than money (to a point). I don't have 10 years to make really small, zero budget films to learn what I'm doing. I feel like I have to spend the money to create an accelerated learning curve. I learned a TON from working with (paid) professional crew. If I had made a feature right out of the gate it would have sucked, bad.
At the end of the day they are resume pieces, building the Gonzo "brand". Will that eventually pay off, who knows, but it's an alternate route to the finish line.
I'm currently writing a treatment for an agent in LA who found me based on one of my short films. Is that likely to pay off, again, probably not, but it does show you CAN get ROI, even if it's not direct monetary return) on a short film.