Being in the military having fairly short hair is a job requirement and many of my coworkers will get a haircut every two weeks. I'm usually a 3-week kind of guy, but I also cut my own hair. Some of my coworkers scoffed at going through the trouble to save on a $10 haircut until I pointed out it's more like $200 worth of haircuts at the end of the year. I save that much each year with an initial investment of $30 for the clippers.
I got commissioned in 2000... 6 years of active duty and another 8 in the guard, I've paid for maybe 15-20 haircuts.
I started *trying* to cut my own hair pretty early, but sort of slacked off after doing a bad job once and being criticized for it. What put me back on the DIY track were a few bad experiences - incredibly slow, AND bad quality - that made me realize I could beat the overall value if I got my act together. I got to the point after a bit of practice where I could do it myself in less time, and better than the average paid job. Now I only pay when I don't have access to my own gear.
I have a CW who likes to go to the upscale sports-themed place where they charge about $35 for a cut, shampoo, massage, etc... my wife even bought me a cert for it after he talked me into trying it once, so I went back for #2, but not long after that, I found MMM and even the occasional indulgence in such things went out the window.