This is so true and a particular job or organisation can change very quickly. I work in a primary school office and honestly, 6 years ago when i started I felt like I'd won the lottery. Despite it being hard work and often stressful for such a crap salary I felt I'd finally found my people and could happily stay there till retirement age. I could manage on the small salary so pay wasn't a factor, i just wanted a job I loved, in the same way others have described on this thread. All the teachers, TAs and other support staff were great, just one big family, SLT were great and we all had a very close, positive relationship with them, we knew our families really well and they seemed to really value us, the culture was just so good, the pupils thrived. I loved working in education anyway but joining that particular school really felt like more than just a job.
Then the head retired early unexpectedly, which brought 4 years of turmoil, ending in a merger between the infants and junior schools which were run separately before, and located on 2 physically separate sites.It was a done deal.
Things have just got worse from an employee point of view with each passing year, with so many changes often for no obvious logical reason - a few for the better but many that have decreased job satisfaction,,increased staff frustration and created more work.
Many long-term experienced teachers have left, the culture has completely changed, the close relationship with SLT has gone - there is a distance there, figuratively and literally and it's hard to even get access to SLT sometimes.
Newer younger colleagues who have started don't know any different, but a lot of the older staff have found it frustrating to witness the decline. Some have managed to stick it out till they can take their pension. I'm a few years off that age but a few things have happened in the last 18 months that I have not been able to tolerate despite giving it a good go and I've become very unhappy in the job, enough that this is going to be my last year.
All it takes is a major organisational structural change and any job can change quite quickly from being one you love to being one that makes you frustrated and unhappy.