I've only asked a question once on Math SE without hoping for an answer (in regards to compactness of the set of densities of equivalent martingale measures, a

I've only asked a question once on Math SE without hoping for an answer (in regards to compactness of the set of densities of equivalent martingale measures, a very narrow topic), when I was completely stuck on it while writing my PhD thesis. To my surprise, I got a very detailed response and a rigorous proof that took me a while to grasp and, on its own, was worth publishing in a journal since this hadn't been previously researched in detail and some authors were even making wrongful assumptions about it. This not only let me finish the thesis, but I've eventually met the kind responder in person. (We were even thinking of eventually publishing this together but never got to finishing it as a standalone work, maybe we should...) // Fun fact: many years later, someone commented on the same mathse topic - "this has been already proven here - <link to the pdf of my thesis>"