Avoiding the IRS and answering the heading question:
Yes, in some strange cases the US government can take 100% of your income. The case I can think of is thanks to the Son of Sam laws and their descendants. If you were in solitary and not making any money stamping license plates but received payments for telling your story, the government could take 100% of that money. There are currently people this would happen to thanks to the conditions of their plea bargains.
There would be other cases for very wealthy people, but that has to do with tax avoidance and we would never get any facts from someone hiding half their money offshore.