BuddyPress.org

“Everyone here as actually looked at the idea not the possibility. I just wanted to know if wp and bp could handle a service like this?”

A lot of the people who have answered mentally skipped over the “is it possible” part because they know it is, the real question is “is the idea viable”, which it did sounds like what you were asking.

Also, some of the people answering in this thread are actively working on sites with members in the thousands… if not millions…

So the advice they are giving is sound.