> Assuming they could cash out and make $5bn, and if they did, who would the losers be?

Your losers scenario requires that SHIB declines materially after the buyers pick up the $5b of the crypto (such that the buyers inevitably end up losing money). You've built that assumption in and it's incorrect to automatically assume that, it's a central flaw in your premise.

There are not losers in every economic transaction in fact. The buyers may end up losing money.