"It's a safe bet you'll learn more in 2 weeks from a seasoned pro than 10+ years of solo butchery."

I really doubt that unless you take the burchery part literally. 10 years ia a long time. The Wrights started their bike building business and build the first successful power aircraft between 1896-1903. It's just a mater of whether a given person likes to self-teach, and whether that makes sense given their circumstance.

The 70s were a different time. It is really hard for people who didn't go through it to realize how hard it was to get decent info on anything. These days the info is all there it is just a mater of putting it into action. The people who went to europe in the 70s didn't just sign up for a two week vaccation, they commited.

If you really wanted to you could braze something in the next 24 hours. Inside a week you could get all the stuff required to build a rack, and build it. It only takes a vise, a file, a propane torch, silver, and tubes. you will learn a lot, though some of it like the propane part is not going to carry you forward for the most part.

There isn't any argueing that the course is the fastest way to get the first bike finished, but I am less convinced many people go on with it. I would be interested to know some names of people who went on to become successful frame builders after a course. A lot of people just go for the entertainment. It's just like the serious bike tourists aren't always the ones who go on an assisted tour of the wine regions of france... That is not a dig, it is great to have the opportunity to do something new and possibly transformative. But it isn't necesarry to pay someone to introduce you to it. It's a choice.

It is also the case that both mentally and otherwise, when you leave the course environment sorting out how you will proceed when you are back home is going to be a big deal. You will still have a ton of issues to sort out around how to make it work out of the home shop. There still isn't a course for that. From what I have seen Doung's take away, like his "jig" is probably more friendly in that regard than some paths.