That is not how insurance works. Insurance will only refund your airfare for certain reasons such as death, sickness and weather delays. You cannot claim insurance because you changed your mind. And in order to make a claim, you have to have documentation, death certificate, doctor's note and or information from the airline that proves you were delayed due to weather. And on top of it all, there may be a deductible.
If your not sure how concrete your travel plans are, either buy a refundable ticket or wait until you are absolutely sure your going.
Now, there are certain times when it is advisable to get insurance. This is mainly for international travel and it is more for the actual trip itself in case you get injured or killed. However, certain credit cards also include this type of coverage so check with your credit card company.