Denny- Yeah, there's more than just IPOs, I was mostly just simplifying. IIRC, you agreed with the idea consumption "drives" economic growth?
Economic growth means an increase in folks' income. Consumption is folks' spending. Increased income could be used on personal spending or a number of other things (saving or taxes, for example), but it's intuitive to think about consumption rising as a function of income. If I go from making $50k to $100k/yr, I'll increase my consumption by some amount. It doesn't have to, but increasing income allows increasing consumption.
The opposite is not the case. It is neither intuitive nor correct to say that I've increased my spending, therefore it is possible for me to earn more money.
Now, at the aggregate level it's true in some way that one person's spending equals another person's income. That's basically the identity property of GDP (GDP as measured spending will = GDP as measured income). Yet that doesn't explain causation. Remember, the concern here is change (growth or decline) in income.
The identity... in economics it's put into a "circular flow model" is pointless in explaining changes because it has no functions for time or productivity.