Take the test!
Whenever anybody questions the capability of my .380 for self defense, I offer to perform the be all, end all test to resolve the question once and for all.
I tell them they can wear as many layers of clothing of their choosing and stand 50' downrange. I'll empty all 7 rounds in their direction and then we'll see if indeed, the .380 is not a good self defense caliber.
I've yet to find anybody willing to disprove that theory.