At 30-40 years old (with the average age around 30, I imagine there are plenty of candidates between 30-40), some small percentage of people are likely to be running into their first health problems or concerns.
Financially speaking, the only thing more ridiculous than the cost of education, is the cost of healthcare. If you need health insurance to cover a prescription that costs a thousand dollars per month, you're naturally going to have serious concerns about leaving the job that provides that insurance.
Like, you'd just have to work a month or two extra before quitting to cover a year of prescriptions.
Specialists usually charge significantly more than primary care physicians and an unforseen trip to the ER can easily cost $20k. It's not as simple as working an extra month or two.
The risks of not having insurance are utterly terrible financial handcuffs. I'm just starting down the path of cancer treatments, the coverages (or lack thereof) and costs are eye-opening, and scary.
Note: I use diverse in quotes not because I don't believe it is important but because what diversity means to people varies dramatically.