Uber is a cancer that has been amassing and burning that investment. Who knows? Lots of smart people at Uber maybe they can figure out how to turn a profit but I maintain that won’t happen until human drivers are not part of the equation or they pivot to something entirely different.

That's a long way away. The self driving technology has plateaued after the initial controlled tech demos and isn't looking likely to be useful in the general way that Uber needs any time soon. Maybe they can get it working in some very favourable routes but not enough to balance the books. Some really hard problems still exist with algos and sensors and the costs will be high for a long time. If the bet is on autonomous vehicles it's a very long bet.

No, paper millionaires. You're only an actual millionaire once you sell your stock. You become a paper millionaire when the IPO happens and you gain liquidity and price increases.

According to your logic there is no such thing as an actual millionaire. No sane person keeps a million dollars sitting in cash in a savings account, they invest it somewhere (equity, bonds, real estate, etc).

Lots of people keep 10-20% of assets in cash.

if you have $20 or $30m, you'd almost certainly have $1m in cash sitting around.

I would be very very surprised if the median person with $20m net worth keeps $1m in cash on a long term basis.