It would make sense if he used to money to buy TSMC or ASML instead.
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If AI matures into the next big thing, it risks wiping them out of their dominant positions if they don't spend to keep pace.
If it doesn't, then they just blew a bunch of money but are still dominant players, with an existential threat in the rearview.
Given the relative risks, they'd be foolish not to pump some of their cash flow into AI for a few years until the pace settles.