If I understand this article, it’s about a 500-page book that is devoted to one proof of one theorem in topology. I find that amazing. And cheers to Quantum Magazine for regularly publishing popularizations of research mathematics. I know many, at times, take issue with their simplifications and framing, but they’re trying, where almost no one else with their reach covers these areas at all.
It's amazing how math can require so much work for what appears to be a single result, but I spend an entire semester proving a single mathematical theorem and to do that I had to work through an entire textbook, so I don't think it's that unusual.
I am consistently in awe of how well mathematicians have stacked layers of abstraction one on top of the other, and how many different ideas end up being very related to one another. Maybe I am romanticised it and the fact that I regret not going for pure math, but there is beauty in all those abstractions that fit together so nicely.