Doing gunsmithing just on the side only non restricted for the last five years and not having a machine I have turned down only about half dozen rebarrel jobs. If you are only doing it part time and as a hobby you probably don't need a lathe or any heavy machinery. If you get into it about 10 percent of the jobs that come my way are just cleaning or reassembling something the client thought was easy to do. YouTube can be a double edged sword about 50 percent is just finding the right part and fitting it in their firearm.
Yeah. I think most guys are really overestimating the actual need for machine tools, and the skills to run them as are actually needed in the day to day of hanging out ones shingle as a Gunsmith.
The skills you need with a lathe, you can learn in a weekend, two weekends if you are borderline stupid. After that, it amounts to how you are willing to apply those skills, and do careful work. Threading. Centering up a part in a four jaw chuck. Turning a decent surface finish. Reading and following instructions. You don't need a Red Seal to do those things. Nor do you need to pee away your life getting said Seal, in order to learn how to do those things, as you will end up doing a lot of things that will never be used at all, if the end goal is gun work.
Hey, I LIKE machine tools! But I don't see the need to be the all singing and all dancing Machinist, as being a really good use of ones time if the end goal is not a job in a machine shop, or running your own ( in which case, business courses are STILL a really good idea!).