There have been a couple studies on the impact of IPOs and the results don't suggest a 50% or 100% increase. If there really are 10,000 new millionaires, it could happen though. I summarized the studies in a post I wrote:
Zillow released the results of a study they conducted, titled "Post-IPO, Home Values Grew Faster in Areas Home to Lots of Facebook Employees." It found that, between March 2012 and March 2013, "home values around likely Facebook employees climbed 21 percent, compared to 17 percent in all other Bay Area census tracts."
Another study written in November 2018, titled “Cash to Spend: IPO Wealth and House Prices,” analyzed the impact of 725 California company IPOs between 1993 and 2017. It found that the impacts were front-loaded, and particularly impacted homes within a 10-mile range of a tech company’s headquarters. This suggests that employees aren’t having to wait for the "lock-up" period to end and sell their stock, and that lenders recognize this future shortfall and will lend accounting for the future gains. The study found that following the issuing event, housing prices went up 3.3 percent, 1.7 percent, and 1.3 percent for a 1-, 5-, and 10-mile radius, respectively. In addition, values rose by 1 percent when a company announced the IPO (compared to the value three months before), 0.8 percent when the company went public, and showed no additional gain after the lockup period.
