SGBoy,
Yes, what you say has an element of truth to it. BUT. From experience, I spend a lot of time on the net at home even now with a wife & kids (course the kids are already big so are rarely around anyway). It's funny though. I can be on the internet for hours while she is watching TV or whatever in another room and I don't feel lonely or bored. But, let her go out to her sisters or rellies for the evening and I'm left all alone in the house. I immediately sense the loss even though when she's there we are each doing our own thing.
So your friends are correct. You won't miss those things until they're not available. And then? The loss become enormous. That's why suicides are higher among singles than married couples (although murders among family members is higher when you are married - but that's another issue). In later years, when one is not quite as mobile as they were in their youth, or the bloom has left their cheeks, it went it will be felt the most and be unattainable then.