alt Hacker NewsIt shifts the gains away from the marginal investor in Microsoft who was only willing to pay a penny less for those shares (probably an eighth of a dollar when this anecdote happened). Instead of them getting the 100 cars, the buyer who was willing to hit the ask earlier gets them.
That profit comes from owning a piece of a productive company, productive companies often spring from early-stage losses that require investment money from somewhere, seed stage money comes from the high likelihood that later stage money will come in if the venture appears successful.
Your comment does not address the (imho reasonable) criticism that the described system incentivizes gambling as the key to wealth, rather than labor.
There are many problems with a gambling based economy, not least among them that over a long enough time line, all the money ends in very few hands.