OP:
teachers take themselves way, way too seriously - you teach kids ffs, it's not life or death. Get over it
Although I think you are an idiot, I actually agree with this observation.
Many teachers with whom I have worked don't take the privilege of being a teacher seriously enough (interestingly they were well-represented in so-called 'better' and/or 'private' schools), and took the p*ss out of the kids & their parents by choosing not to work hard or care about the kids in front of them. You are correct, it is not (usually) life or death.
However, the majority of teacher with whom I have worked put heart and soult into the (very challenging) job which is teaching, and therefore DO take themselves seriously ... most decent people would, if they had to deal with the range of issues which present themselves with kids.
You can choose to ignore the childrens' wider interests, and bugger off at 3.30. Some of my colleagues do. However, those of us who stay until 6 or later and do the job properly are justifiably proud of what we achieve.
Lucky for you & everyone else in society that we choose not to take the p*ss just because we potentially could ... ?