I agree that if your own health and that of your family didn't depend on your employer liking you, true at-will employment would be a lot more realistic. Right now many people are afraid of rocking the boat too much or to stand up for themselves because in case they get fired they might go bankrupt in case of an accident (I think realistically it might not be as dramatic, I think COBRA retroactively applies to whatever issues you might have encountered in between real health care plans).
If your manager doesn't care about work-life balance and is perfectly happy with making you work 60+ hour weeks without any sort of compensation, be it in money or time-off, your best bet is to start looking for a different position, possibly at a different company. That way you at least do not lose health insurance.
In any case, yes, being afraid to lose your job because you don't know how to pay for a basic need such as being healthy is absurd in the First World.
What if you have a chronic illness that will never allow you to be "healthy" regardless of what lifestyle choices you make? Additionally COBRA allows you to pay the full unsubsidized cost of your insurance, not your normal subsidized premiums. As far as employer culture, that is something you really do not understand fully until you've been on the job for awhile. You could very well end up in a worse position than the one you left. You can't just say "I don't like it here, so I am going to go over there for awhile, if it doesn't work out then I'll come back'. No. It's a risk & the risk is your livelihood & possibly your health. All are reasons people don't just bail when the job starts going downhill.
If your manager doesn't care about work-life balance and is perfectly happy with making you work 60+ hour weeks without any sort of compensation, be it in money or time-off, your best bet is to start looking for a different position, possibly at a different company. That way you at least do not lose health insurance.
In any case, yes, being afraid to lose your job because you don't know how to pay for a basic need such as being healthy is absurd in the First World.