OP, Let me ask you a question.
If you are holding 1 bitcoin or less in your wallet, which you never planned to sell out any time soon, your family is doing well, and there has never been any need for you to need extra cash. 

If you wake up one morning and your child is in a critical condition that requires immediate medical attention, you rush her to the hospital, the doctor confirms that she's going to need to undergo some surgery in the next couple of minutes, and you don't have such an amount of money demanded right on your bank account or in cash, but you have some Bitcoin stock somewhere, what will you do? Do you really need to think about what to do? The more time you are spending thinking about whether or not to sell the Bitcoin and save your daughter's life, the more you are endangering the life of that innocent girl. (just an illustration). 

Situations like that don't even require a second thought; sell off and solve the problem. That's the most important part of saving: for our savings to save us in the future in times of need. If you keep on calculating whether or not you are to stake your savings over saving the girl's life, you might end up regretting your actions for the rest of your life. 
Your question is just so unreasonable. The answer is yes, sell and save the kidnap victim. You can save up with time.