There is a tremendous failure on the behalf of universities in the way they hire academics and how they treat them.
Universities preferentially hire world class _researchers_ so that they pull in maximal grant money which they can then leech upwards of 70% in dramatically overstated "lab fees". Then, they force these researchers to go through pointless habilitation exercises and then teach classes which, the vast majority of the time, have nothing to do with the academic's research. A new professor will likely be forced to teach the most advanced classes that are not specialty classes (in physics say Electrodynamics, or Quantum Mechanics) because no one wants to teach the hard subjects that aren't their own field. This means that the new professor, for the first several years, will spend 10+ hours a week studying the concepts themselves to they can adequately teach the class.
Then, in most situations, the academic, on tenure track is simultaneously forced into a support administrative position. They are required to arrange anywhere up to half a dozen business trips a year which entails days of planning, applying for permission, purchasing fare and lodging (of course out of the researcher's own pocket), applying for reimbursement, etc. And god forbid you host a meeting yourself, that has a whole slew of it's own responsibilities. Then of course there's the day to day applying for major grants which you need to do yearly, applying for purchase permission for lab equipment which, depending on your lab can be once every few years (computer labs) to once every few weeks (geophysics for example buying reagents). Also you need to organize and attend anywhere from 1-10 meetings / invited lectures per week.
This person, who has gone into academia because of their passion for a specific aspect of their field now spends the vast majority of each day micromanaging students, studying a topic they don't care about, teaching that topic to a class of students who likely also don't care, filling out redundant and often confusing legalese style paperwork and teaching the exact same skills over and over again to the steadily coming and going research assistants.
And _none of this matters a tic on the resume_. All that people care about is the paper output, which is what the researcher wanted to do in the first place. Is it really a mystery as to why your undergraduate professor seemed pissed off and stressed out?
The problem is universities hiring world class researchers to do administration and teaching when they should be hiring administrators and teachers. Researchers should work at research facilities like Fermilab, CERN, NASA etc. Does it really fucking matter if your Physics 1 professor got a Nobel Prize back in the 60s?
Also most academics I know don't share your perceived opinions of looking down on undergrad students, the general public, grad students, etc. Most of them are just really disappointed that they can't do what they got into the business to do and are used to dealing with people who don't care about them or their passions at all.