The potential reward for putting it in something riskier is enormous. You and I might consider $7 billion/year to be plenty and there's no point in chasing high

The potential reward for putting it in something riskier is enormous. You and I might consider $7 billion/year to be plenty and there's no point in chasing higher returns, but we tend not to be the sort of person who is in the position to control a fifth of a trillion dollars in the first place. Investing it in something riskier to make more money would be foolish but it's also something that's been done many times before.