Is it better to borrow cash using BTC as collateral, or just to sell BTC?
Don't tell me everytime you have an income of bitcoin you always say that is borrowed from others.
I did not come from the USA but in my perception, it's better to pay than to punish if you are caught by the government in the USA.
Borrowing means no income = no taxes.
Is it right?
Your right, you can do this just once or maybe twice but careful by next time that's a part of illegal activities. Is it better to obey the law than if you caught and put in a jail for punishment right?
Yep, better to follow the rules than to regret later. You cannot escape the tax easily especially in US. Borrowing money is not consider as your income but the money that you will be used to pay for that comes from your income for sure. Sell your btc only if you badly needed the money and pay taxes for you to be a good citizen of your homeland.