[bayesian_horse]

You are running into the fallacy that you can know what is a bubble and what is not, before the fact.

[danieltillett]

Not at all. We know in hindsight that the pre-2008 run up in prices was a bubble, but at the time this was debatable. I am just trying to explain to the OP that prices are set by supply and demand, but that demand may not always be rational.

Personally I do think it is a good idea to try and avoid speculative bubbles in assets and the best way to do this is via taxation.