>>63957366 (OP)It's not a scam, but what SDI sells isn't really a great product/service either. Overpriced at best, and the "degree" you get at the end isn't worth the paper its printed on.
SDI promises distance learning courses that'll teach you the basics, and they more-or-less deliver on that.
However, you can learn the exact same shit for free by watching some youtube tutorials about woodworking and metalworking, as well as borrowing books skills specific to gunsmithing from your local library, or downloading old public domain gunsmithing books from PDF archives. If you've got questions that aren't in those books there are still forums filled with old boomers that mostly know what they're talking about.
As for the physical materials, the starter kits SDI sells are just basic tools available cheaper from companies like midway USA or Brownells.
If you want to get started in gunsmithing, your best option is to either become an apprentice for gunsmith (unlikely to happen unless you've got family connections, or you already have related skills like metalworking or furniture carpentry and you can show off examples of your work to display your skill level), or attend one of the few trade schools that still offer courses in this shit.