Have them use Hush, or any number of the in-browser GPG/PGP extensions that will encrypt your gmail then! At least their webmail is encrypted then (and Hush integrates with most of the notable PKI servers). You have to start them somewhere, just lamenting about it isn't going to change anything. I've moved my family and friends into GPG over the lsat few years and now I receive GPG-encrypted mail more often than not.