Presumably this makes money for specific people selling bitcoins?

A strategic oil reserve is an actual thing you can use instead of buying it abroad should it come to pass buying it abroad becomes problematic or expensive.

A wealth fund is for folks with a surplus in order to get value out of their investment.

Unlike BTC these things make sense. This is gambling.

TX is preparing for more waves of USD inflation. The conventional understanding is that Bitcoin allows its holders to protect themselves from massive waves of currency debasement. A Texas Bitcoin Reserve throws a massive power re-distribution back into the its hands and out of the those of the Federal Reserve System. Sure, TX could 'hodl' their oil, but sometimes it's good to have a digital savings technology that cannot be debase.