Probably because people want to spend what they make. If you live in SV, you see people driving Teslas, and you think, "I want to do that too." So, next time you fly first class for the family vacation, and stay at the pricey villa. On your next trip, you add a couple of private tours, and can't find a good return flight, so you buy some NetJets credits. Next thing you know, you're spending 65k/year for a nanny (to support those high-paying Google T6 jobs), and it's eating into the 200k/year savings it would take to reach that level of wealth.
Most people end up spending close to what they make. Most people don't save like what 100M would require you to save.