Seems most here are talking about 'money' when the title asks a different question, i.e. where does the 'wealth' go?
Oftentimes percieved 'wealth' doesn't exist in the first place: it is only, in the words of PIMCO, a 'state of mind.'
I give you two simple examples:
1. Suppose there is a stock WLTH that trades on Nasdaq. Well, it is a very thin issue - for simplicity sake lets say it doesn't trade at all, but the market makers always quote on both sides of the market. Now imagine there is talk of a one or more tender offers at much higher prices, so market makers quote the shares very high, and the condition persists, again with little or no trading activity, i.e. no money is changing hands.
Shareholders may perceive that they are 'wealthier' because they can ostensibly calculate the value of their shares. Thus, they may become more profligate spenders, borrow against their shares, or otherwise take more risks.
Finally, assume the company adopts a poison pill and suitors all walk away. Thus market makers bring the quotes down dramatically, but again without any meaningful trading activity.
What happened to the wealth??? It only existed the minds of shareholders. It altered their behavior. And it vanished in the blink of an eye. Most importantly, that 'wealth' had only a tenuous relationship with money.
Example #2. Bob and Slob live next door too each other in $100k houses. Now suppose some numbhead overpays for the house across the street - say he pays $200k. Realtors knock on Bob and Slob's doors and tell them their homes are worth $200k and show them questionable appraisals to that effect. Suddenly Bob and Slob both feel wealthier. Bob convinces a mortgage lender to lend him a total $150k on his house based on the appraisal. Slob puts $50k on his credit card to buy that boat he wanted, comfortable in the thought that he can take a second mortgage if needed.
A year or two passes before all realize the house across way is only worth $100k like all the others, buyer only paid more because, as it turns out, he thought there was a seam of gold running underneath that specific property and he needed to get an old lady to move out of the home she was born in. When he didn't find the gold, he dumped the house for $100k.
Eventually Bob gets transferred out of state and puts his house on the market. Uh oh, he has $150k mortgage on a $100k house. Slob has a new boat and credit cards he cannot pay off. Both of them held imaginary wealth. Where did it go? It never existed in the first place - it was only a state of mind.