Why, though? Fundamentally? Approval =/= launch, and approval =/= demand.

As one example, when the CME launched BTC futures last year, the price crashed. It's all about timing.

Bull rallies are born based on supply/demand imbalance, not hype. Hype comes later, after the price is already skyrocketing. If an ETF approval comes after an accumulation period where long term supply has been absorbed, then yeah, it could spark a legitimate new bull market. But if the bear market hasn't run its course yet, I wouldn't plan on it.