need to include airfare in travel insurance if refundable fare

[CCJack]

I recently booked a cruise and also business class airfare through Lufthansa.   It was only a small amount more to get business flex - which is refundable as compared to their normal business which is not refundable without penalty.   My question is for travel insurance is there benefit to including the airfare if it already refundable by the airline.   Perhaps if there is an issue with air travel and you miss your cruise - then maybe travel insurance would not cover if you did not include the cost of the air, or some similar situation.   Any advice would be appreciated  thanks.

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