Alphabet holds approximately 551 million shares of SpaceX (trading under the ticker SPCX), valued at roughly $94.1 billion, which represents about a 4% to 6% stake in the company.
PlanetLabs is the company providing the satellite bus infrastructure to Google for this project.
A bank run happens when everyone tries to withdraw all their money at the same time and the bank runs out of cash. Not really possible in the stock market where companies literally can create/destroy shares and there is a whole secondary pricing layer to it.
1. https://www.reuters.com/business/finance/alphabets-spacex-be...
Didnt you answer your own question? Most would consider a 100x ROI more than sufficient for taking profits
They've not got a pressing need for the cash, so can afford to take a multi-decade view of SpaceX. If you look at other investors who take a view across that time horizon, you'll see some pension funds and huge trusts putting money into SpaceX for the same reason.
It's overpriced today on fundamentals, but in 50 years time, today's price will look cheap.