Anecdata: quit my job at age 29 to go back to get a Master's in EE, studying neural networks, in 1996. Quit my job in the semiconductor industry in 2004 to become a programmer at a university. Quit my job at the university in 2010 to go into the private sector. All three turned out to be the right decision, as far as I can tell, but in all three cases I was mostly motivated by knowing that if I did not, I would regret that more than I would regret quitting a position I was no longer interested in.
But, I wonder if it would still work well if, in the back of your mind, you were thinking "but it won't really fail, it always succeeds". You really do need to take seriously the idea that it will not work out, and only do it when you would still rather try it.