yes that last sentence surprized me. but i understand it.
if you have spent 30 years or so training yourself to do math and teach it to other like minded people, it is very stressful to be faced with 30 more years of trying to interest students, some of whom hate the topic and just want an A without doing any thinking.
thats why sabbaticals are a good idea. at schools without them, we depend on the rejuvenation of summer activities, conferences, colloquia, physics forum, etc...
another thing that seems to help is to learn not to judge people for their different attitudes towards a subject we love. to care about them and enjoy them as people, and then maybe if they begin to like you and your acceptance of them, they may ask themselves what it is about math that interests you.
this may seem almost somewhat saintly though, and recall he said somewhere "they don't pay me enough to be a saint". actually trying to adopt saintly patience is maybe impossible, but still helpful.
no matter where you are, eventually you may feel used, or underpaid, or unappreciated, or even disrespected. so it is crucial to do what you do for the love and enjoyment of it, not for prestige, nor money.
at Harvard the students are as good as anywhere, and the profesors are also, and they have relatively good pay, good conditions, and time for research, and collegial stimulation that is almost unrivalled.
still at 70, even the most respected professor is forced to retire there, regardless of activity level. if he has been dependent on that title of Harvard professor instead of joy in his work, this is very hard. he realizes he has been considered a commodity by his university, one which has exhausted its value.
but the intangible community of mathematics and mathematicians just continues discussing matters of interest.
maybe this is nonsense. I am just saying i understand Lee Lady's frustrations, have felt them, and have tried for decades to resist giving up the fun of doing math, and also to not give up the sense of community or being a teacher and member of a university myself.
at UGA we have several retired members who continue to come in and do research in the department, something i never saw at Harvard. this is a good sign. in fact Matt Grime is coming next week, currently from Princeton, to chat with some very active members of our group, some retired, some relatively young.