Full Idea
Some critics say virtue is not necessary for eudaimonia (since the wicked sometimes flourish), and others say it is not sufficient (because virtuous behaviour sometimes ruins a life).
Gist of Idea
Virtue may be neither sufficient nor necessary for eudaimonia
Source
Rosalind Hursthouse (On Virtue Ethics [1999], Ch.8)
Book Reference
Hursthouse,Rosalind: 'On Virtue Ethics' [OUP 2001], p.172
A Reaction
Both criticisms seem wrong (the wicked don't 'flourish', and complete virtue never ruins lives, except in tragic dilemmas). But it is hard to prove them wrong.