Can I lose any ships to 3 star a Ship Challenge

You need 8 ships as a requirement to unlock the challenge. It doesn't mean you need 8 ships to complete the challenge.

I honestly don't understand how complicated this is to understand. If they made the requirement only 5 ships, then MORE people will be able to do this challenge. The game wants to make the requirement "longer", "more diffcult", etc to make you grind for more ships and make you "earn" the challenge.