Economics 101

Whenever anything happens in the World, we can always look forward to what the City thinks of it as share prices go up or down and the news stations wheel out some braying nugget in braces to explain to us plebs that an earthquake in China means a drop in the underlying inflation ratio of fruit production derivatives and therefore we will have to close another hospital.
As we are relying on the same people who put us in the hole to get us back out again, obviously we hope that the flake with the tie-pin that cost more than most peoples houses knows what he is talking about but when did we move into having to rely on what the markets thinks, when did how the economy work change from what we were taught at school?
I distinctly remember sitting there in the mid 1980's writing 'I love Andrew Ridgely' on my pencil case and pretending to listen to a teacher explaining that the economy is all about supply and demand and unless i was absent that day, not once was it mentioned that the livelihoods of most people on the planet seem to depend on the actions of share dealers and if one day the traders spend all day buying instead of selling, this leads to a global slump. When did that happen?
Also, if everything relies on what the share dealers are doing on the stock exchange, why were they not watched like hawks so they couldn't cause such a global mess of things and we end up with millions of lost jobs and lives ruined and made homeless just because some dimwit shouted sell instead of buy.
Then again, i did have a bad bout of tonsillitis during my last year at school and missed about a fortnight of schooling so maybe that bit was covered then.