# Breaking of electroweak symmetry at loop level

I was thinking that one could write down a loop diagram with a top loop and 3 external neutral Higgs particles. Since the Yukawa interactions are also present when the electro-weak symmetry is restored at high temperatures this would give us an effective $$hhh$$ vertex and break the electroweak symmetry. Why can this not happen? In particular the top Yukawa coupling is also order 1.