My family is quite supportive. My wife is comfortable with my buying decisions, as I've been able to demonstrate that more often than not I come out ahead when it's time to sell something. In other words, I'm not sticking money down the proverbial rat hole to pursue this hobby ($ tied up, yes, but we both have seen that this stuff is closer to an investment). She also knows how much I enjoy restoring, repairing and learning about electronics via these vintage audio units. Finally, she knows where I am - at home.
Now the fact that there are 50 or more vintage components in use or on display in select parts of the house does not necessarily delight her, but I try to keep things reasonably organized and attractive and she bears with it for the reasons set forth above.
My 15 year old son does not say much, but seems pleased that the old man likes to crank up the tunes on a good sound system and is certainly not embarrased to show off the collection to his friends. He has benefitted due to this hobby and has a vintage system of his own, including a classic Marantz CD-73 CDP and a pair of Altec Lansing 515 speakers (floorstanding ones with carbon fiber cones? I really like them, near mint at a GS for $5). I've offered him his pick of (almost) any of the other receivers to replace his Technics SA-5360, but he says he likes the system as it is.
My daughter is totally indifferent, as long as she has reasonable sound she is fine, so dad's hobby once again provides the method of delivery.