$100m is manageable, if you've got 100m paying subscribers or companies using your API for a year you can recoup the costs, but there aren't many companies with 100m users to monetise for it. $1B feels like it's pushing it, only a few companies in the world can monetise, and realistically it's about lasting through the next round to be able to continue competing, not about making the money back.
$100B though, that's a whole different game again. That's like asking for the biggest private investment ever made, for capex that depreciates at $50B a year. You'd have to be stupid to do it. The public markets wouldn't take it.
Investing that much in hardware that depreciates over 5+ years and is theoretically still usable at the end, maybe, but even then the biggest companies in the world are still spending an order of magnitude less per year, so the numbers end up working out very differently. Plus that's companies with 1B users ready to monetise.