For one thing, I've only been a public servant for the last 2.5 years. I've spent the rest of my working life in the private sector, including nearly half of that working for myself in my own business. In the last piece of work I did with my own company, I earned £25k for 3 months work, a piece of work that involved a corporate reorganisation, trying to make as many people redundant as possible.
Now I earn half that and have to work a damn sight harder for that money than I did previously. But I love it and I know the vast majority of my colleagues feel the same, plus there's the pension, which adds about 20% over what i'd get in the private sector. There's also hugh intangible benefits that you can't put a price on, including the massive development opportunities available to me, and the scale and complexity of the work on offer.
Many public servants do feel undervalued and with good reason. But their pride in their work, and the satisfaction serving the public gives them, keeps them going. But if you want decent public services, that comes at a cost.