I am self-taught, but had early music and woodworking training. A tough way, I was young, no internet, information came only from books.
A good number of makers we love today had no teachers. Life in Italy was hard, and they had to struggle to survive working as a violin maker, player, cooper, teacher, etc.
Stablishing yourself as a self taught maker today will be hard, since the market is highly competitive. Learning restoration work in a high level as a self taught it is almost impossible, I think.
In general, biographies will not mention "self-taught" directly, but just mention that the maker "got some advice from the Bisiachs..." (in Eric Blot's books we read "prese qualche consiglio da..."
This is a small list of self taught makers or "diletanti" (at least in the initial of their career), and they represent an exception when we consider the number of such makers:
Giovanni Battista Guadagnini
Stefano Scarampella
Sergio Peresson
Andrea Postacchini
Gaetano Sgarabotto
Otello Bignami
Romolo Parmeggiani
Gaetano Pareschi
Alberto Guerra
Giuseppe Pedrazzini
Celeste Faroti;
Luigi Bertelli
Andrea Cortese
Gaetano Chiocchi
Valentino de Zorzi (an important florentine maker that started making violins when he was 40 years old!)
Anibal Fagnola
Emidio Celani
Howard Needham said me he is a self-taught maker too.
Some say Lorenzo Storioni had no master too, as well as Giuseppe Rocca.
The ever increasing prices of their instruments is a question of market, and after some decades, market disregards formal training.