Lol......I don't fail, so it's not a problem.....J/K.I've searched YouTube for "CNC fails". I hope you don't post a video of one soon, haha.
Most guys fail at the setup portion and also posting the G-code which is sometimes tricky. Plenty of guys attempt CNC retrofits and fail, but this was a new system designed for CNC that simply needed rebooting and some fine tuning/cleanup work. Even then, it wasn't turnkey. The goal was always to have a prototype option. The main problem I had was the CAM software that could do what I wanted without costing a fortune wasn't available. With Fusion360 the software is massively capable for $460/year.
The Rapid prototype thing, it was always a backup to my plan. Back in 2009 I bought the CNC with the intention of doing exactly what I'm intending now, but then I got in over my head with work and the software limitations. I highly recommend to anyone to PAY the money and buy a turnkey setup, delivered with basic tooling package and software ready to go. I made the mistake of piecing together a system that sort-of was complete but not ready to run. That's getting corrected now. If I can start running good parts in 6-9 months with my somewhat complex component designs, I'm fine with it.