I was at a NGO for a while where we interviewed North Korean refugees about execution and burial sites and collected the information in a PostGIS db with QGIS as a frontend and working towards a custom UI plugin for the interview process, and it was very rewarding. Their operations also had a lot of unique security challenges to deal with.
Working late because people are dying is a much better justification, but you will burn out just as fast. People who are too earnest about a cause have difficulty pacing themselves. Every org has people who burn the candle at both ends.
The world as a whole is still trying to work out how to be productive enough to provide for everyone, fairly or reasonably divide up the pie and achieve the vaunted work-life balance.
That's a relatively new concept. In the past, a lot of people were literally slaves or metaphorically "wage slaves." A standard expectation was that the man of the house was the primary breadwinner and he had a wife handling all the quality of life work -- cooking, cleaning, shopping -- so he could put most of his time and energy into the job. In exchange, he got enough income and benefits to support a family.
We are gradually transitioning to a two income couple model in part because people are living longer and having fewer kids. It no longer makes sense to sequester female labor and limit it to women's work. It doesn't make sense for her life, for her marriage or for society.
The transition is proving bumpy.
It can be all the stress of working for a tech company, with 1/3 of the pay. The dynamic that often shows up is that higher-ups try to use employees' intrinsic motivation to guilt them into working longer hours and accepting low pay, "for the greater good".
There are good and bad NGO workplaces, just as there are good and bad private workplaces. But NGOs as a whole are no safe haven.
Not saying there aren't great NGO roles, but the company being an NGO isn't a good signal that it is a great role.