tech bubble was obvious at the time because earnings were far far behind valuations, it was hoped that earnings would catch up and business models were sound, in most cases they weren't.
Commodities? that's supply and demand.
There are no derivatives in iron ore...that's real economics at work, not speculation.
Industrialisation in Chindia will consume enormous resources and energy but the process isn't ending, it's still early days. Look at history, post WW2 in Japan. took decades.
