That's the line they gave all my peers who went into public interest and non-profits. Most of them left from burnout or because the low pay and high demands were exploitative.
Here's the trick these mission-oriented employers don't want you to know: you can use the freedom that money affords in order to build meaningful and fulfilling aspects into your life outside of work.
That’s what they want you to believe so they can pay you less than Google. Meanwhile the googlers got rich and are doing fulfilling and meaningful work on their own pace once they quit.
I assume people find meaning in different ways (perhaps I was being unfair to the tech-advertising business). I've always thought the Library of Congress, Smithsonian, NASA, or the National Park Service might potentially be amazing places to work, depending on the role. Looking at a full list of federal government agencies it doesn't seem crazy to me that people could find meaningful work in some of the others.
Nothing as meaningful as maintenance programming at Google, of course. At least the paychecks wouldn't be as meaningful.