I have only spent Bitcoin on legal things. Rent, food, flights, and hotels. I think you have a cognitive bias-- there's no indication that a significant part of the Bitcoin economy is related to crime. Most of it is on the up-and-up. Some of it isn't, but that's the same with every currency.
How have you accumulated those bitcoins?
Only through activity which does not violate the laws of my legal jurisdiction.
But they probably violate the law(s) of some of the jurisdictions that your business service. Which make them funds gained from illegal activities.
Also, did you report 100% of your income on your taxes? Even if you made bitcoins and spent those bitcoins without them ever hitting your bank account? Because if you didn't report every single bitcent that you made, that's called tax evasion and that's also illegal.
I currently have no tax liability at the level of income I make, officer.