1.  What Mig said.  Taxes are on profits, not trades. The tax on trades is just commissions which are virtually nothing these days on computer executed blocks.  Plus the bid/ask losses.

2. your contention that the entire market is a bubble at the moment is not supported by the facts as I see them.

The average P/E of the S&P 500 is only 16 X if the Yahoo financial page is accurate.  That implies a 6% profit across the big companies that are probably 80% of the market value.  It's been lower when interest rates are much higher but this is hardly Ponzi leverage.  You are grossly overgeneralizing.

You are comparing the apples of Enron/CMGI/Lucent with the oranges of Coca Cola, Merck, etc.