[delfinom]

A bubble doesn't mean the underlying demand/industry doesn't exist.

It means there's a mass over investment and over spend in companies trying to serve the demand at the time.

[Ekaros]

And that current valuation of the underlying market is x times the real valuation. And real valuation can be significantly non-zero. Take housing market. Most of the houses do have some real value. And even if the bubble pops, it doesn't take their values to zero, it might be momentarily be just below real value.