It's not clear to me why you think "I refuse to do the thing you're asking me to do" is _less_ reasonable than saying "I will only do the thing you're asking me if you pay me $large_amount"
To me, the latter response is perfectly reasonable. There are plenty of tasks that I wouldn't want to do as part of my regular work duties, that I would be happy to do in exchange for the right bonus check.
If a manager is looking for someone to perform the task, and they decided to _fire_ an employee because they said "I'd do it for $X" instead of saying "No I won't do it", I'd say that manager was either on a delusional ego trip or looking for another chump to exploit.
To me, the latter response is perfectly reasonable. There are plenty of tasks that I wouldn't want to do as part of my regular work duties, that I would be happy to do in exchange for the right bonus check.
If a manager is looking for someone to perform the task, and they decided to _fire_ an employee because they said "I'd do it for $X" instead of saying "No I won't do it", I'd say that manager was either on a delusional ego trip or looking for another chump to exploit.