Can you provide sources or any meaningful numbers beyond handway 'most' regarding which of his shares are used as collateral?
His NW went from 20B to 270B in last 2 years.
If your house went from 200k to 2.7M, the bank will somehow find it in their heart to lend you a lot more dollas than before ¯\_(ツ)_/¯
Doing the actual maths 40B is chump change and he could probably borrow couple hundred B or more if the things he's buying also have market value banks will lend on.
Unless he's somehow borrowed hundreds of Bills in the last 2 years? Any sources for that, I looked because of what you said but didn't see any actual info on loans beyond .5B in 2020 which is a fifth of a percent of his NW. Literally < 1% of his NW ??