People drop dead in Japan from their jobs frequently as well, regardless of industry. This hasn't anything to do with the job being hard and everything to do with work culture.

I acknowledge that investment bankers have a toxic work culture, but I don't believe the job is inherently harder than teaching, which is unavoidably hard in many ways. Some of the ways are solvable by having more teachers (smaller class sizes, not needing to take work home), but not all of them.