The .380 is the smallest cartridge that most will carry for self defense. It certainly isn't a .45 acp, but the .380 lends itself to small pocket guns that allow you to carry a gun when larger guns won't do.
As with any gun, shot placement is key and a .380 gives you less of a margin for error than some of the more powerful handguns.
"He who laughs last, laughs dead." Homer Simpson