Ben's challenge was to name the date of the collapse of the bubble, and suggested that without that, there was no meaning to the phrase that we're in a bubble. Steve gave a large range (5-10 years) and changed the subject.

Ben's point was that if the bubble burst is 10 years out, then right now, the right thing to do was to invest -- that there was still a lot of real growth coming before over-exuberance set in, and I think that Steve is implicitly agreeing with him.

Ben's argument is a bit odd, because you can't predict the end of the bubble.

If you say 10 years, people start pulling out 9.5 years in. But, knowing that, smarter people will pull out 9 years in, hoping to beat out the people pulling out 9.5 years in. Then...well, you get it. Game theory. And that's how bubbles become unraveled.

I think his point is that saying we're in a bubble should mean that the right thing to do now is divest, because you can't precisely pick the date that it will end. It might not be immediate -- you might want to ride the bubble a little -- but you should be basically assuming that at any point, the over-valued companies are going to pop, and look to getting out of them.

If the right move now is to continue to invest -- then that means that the valuations are not bubbly.

So, 10 years to a burst is way too far out to cause you to divest right now, if we are going to have 10 years of growth before then. Even 5 doesn't mean we're in a bubble now, so Steve saying 5-10 years is the same as saying, "we're not in a bubble" (according to what I think Ben means). I think Steve understands that too -- and that's why he changes the subject.