As to "freedom to choose my research topics":
How can you justify to yourself to take money from the people at gunpoint to research bitcoin for hundreds of hours? How about researching wasteful spending by tenured professors?
Hint: I am a professor of
computer science. Guess where the idea of bitcoin came out of?
And methinks that if I could prevent a few folks here losing their life savings to scammers, Brazilian or otherwise, that may already justify my salary. Which may be more than I deserve, but is not exactly taken at gunpoint from them,
Tax money is ultimately taken through threat of force. You can tap dance around that all you want, but it's the truth. Most private and public sector scammers really believe their own bull shit. Rationalizing the evil we do is part of the human condition.