Call me cynical and jaded, but I don't believe "building something valuable" is the point of employment.
"Building something valuable" is the point of my vocation. I used to believe that the employment and vocation should align. Over the course of more than 20 years of my professional career, the vast majority of the employers I've had have done their best to disabuse me of that notion.
The way I see it, the point of employment is to ensure you have the money and the benefits you need to live comfortably. If your employment and your vocation align, it's a nice bonus. If they don't, do what you're passionate about in your free time.
> Many hackers want to both provide the best possible life for their families and participate in a grand adventure of changing the world by creating something people want.
If you can get that, it's awesome. But if you can't, then you have to choose. And I know what I'm choosing.