Wealthy do not stash, they or their parents got wealthy by investing. Businesses go offshore to avoid high US corporate income taxes. Under the FT, taxes on income, corporations, capital gains, social security, medicare, self employment and estates disappear.
Without the assorted taxes on capital and income, investment will flow in volumes unimaginable even in the 19th century. Business will fire most of their corporate attorneys whose only job was to figure out ways around the current byzantine system. The business of business will once again be to make money and not how to avoid taxes.
In 1998, Merrill Lynch estimated that world wide, 5 trillion dollars was stashed in off shore accounts and that amount represent nearly a third of the wealthy's savings.
However, that's not the point.
The point is that a 30% consumption tax will be distortionary. It will change people's behavior. The effects will be good for some and bad for others (not just tax attorneys). The wealthy will find ways to consume that avoids the tax, just as they find ways now to avoid the income tax, corporate taxes, or whatever.
Ah, the golden age
Without the assorted taxes on capital and income, investment will flow in volumes unimaginable even in the 19th century.
It was also the age of recessions, depressions, gave rise to the labor movement, and ultimately - the income tax.