Where you stand depends on where you sit, so I understand Sam's annoyance with the question of bubble / no bubble. And I get that the tech media knows that it's a reliable source of pageviews. But it's not a spurious concern. Anyone who's got a 401K should be rightfully concerned, because asset managers of all stripes are now jumping into the pool. Zooming out, anyone who has a passing interest in the U.S., and indeed global economy, has a right to ask because the valuations are definitely being driven in part by low interest rates that our central banks have resorted to -- which are hurting savers, pensioners and anyone else on a fixed income. And if it ends badly I don't believe for one second that the hurt will only be confined to those with skin in the game. The global economy is far too financialized and integrated to hope so.