I keep the discussions limited to my internet friends on MMM and the Early-Retirement.org forum.
Even my parents probably wouldn't understand! (my mom might, but my dad wears the pants in the family, and calls the shots). Dad is 71, more than enough money to even keep track of, and still works part-time at the family business to suck up as much additional money as possible...but if I were to tell him I have "enough" (a mere fraction of his) and don't need to work, part of me fears he would probably think deep down that I'm just waiting for him and mom to keel over to get my share of the inheritance. He knows that my fiscal attitudes (live far below your means) are close to his, and that my 2 sisters and brother are various levels of spendthrifts - but I'm still not going to risk mentioning the concept of ER.
I haven't even mentioned my NW to him, although I might get around to it someday (it's more than he likely suspects).
Siblings? Not a chance - in addition to being somewhat spendthrifts, they'd run and tell dad, and likely spin it into some form of "he's just lazy and waiting to get his hands on your money".
Friends in real life? I've tried touching on a few money topics when they bring it up....but whether it's ER or trying to explain why that "some sort of guaranteed annuity thing" their financial salesperson sold them isn't any good, it's the same result: glassy eyes for a second, before quickly wanting to change the subject and not even wanting to talk about it.
Co-workers? Just as with the general population, mine are no different in their spendthrift ways. One of them thought aloud one day (when recalling a story about a neighbor when he was younger), and seriously suggested that the key to accumulating wealth was 'never throwing anything away, because this neighbor never threw anything away and had tons of money'. Yes, he was 100% serious in his theory. After finishing his story, he promptly went out for his daily lunch at some restaurant.