Don't get mad at people who invested a lot in the Bernie campaign. Don't "I told you so", don't insinuate they were stupid for believing in bourgeois electoralism. Try to be kind.
A lot of people are realizing right about now that the US is a country where wanting something as reasonable as free healthcare means you're banned from national politics for not being right wing enough. That stings a lot, and some people will need some encouragement in order to not fall into hopelessness and despair.