I had a language tutor for a number of years and did not progress to fluency.
I've seen that many language learners, once they get convinced that they can learn a new language, go on to learn multiple languages.
I do not have a tutor and the same time spent with them has now passed. I have certainly not progressed as much as I did with them.
TL;DR: Do the majority of polyglots use tutors at least at the start or are they self taught?