You're talking pure ideologues here, even the thought of making an easy buck off of publishing they will instead eat it and take the story of corruption to their grave for the team.
Not everyone in government are fanatical/committed ideologues. And even some who are may decide its time to cash in on this one time opportunity to fund their retirement, recoup expenses from a divorce, pay for college, get that second vacation home, etc. Most of the liberals I’ve known are elitists and hey love and crave money. They would drop a dime on anyone if it meant they could live a higher lifestyle. And if the country should take a hard turn to the right for some reason, what have hey to lose? May as well rake in those easy bucks while they can. Trust me, it will happen.
Not necessarily just the idealogues.
Acquaintance of mine was an "economist" for the state legislature. Her job was to fudge the numbers and make powerpoint presentations to the committees. She got paid well. She wasn't going to blow the whistle on herself.
That's how they suck you in - they get you in a position where your livelihood depends on them and they know that you know you're in it just as deep as they are.