The money required to double the bitcoin hash rate and maintain double is immense. It's specialized hardware that would need to be manufactured (lead time while network continues to grow, plus who even has the capacity to do that other than TSMC or Samsung) and the network would see it coming and have a chance to do something about it.

It was a risk when it was smaller, but the ability to pull an attack off like that now and maintain the attack isn't practically in the realm of possibilities. (Edit and that's not even getting into where they'd get the power to power the network which is estimated at 173Twh a year and the need to keep expanding that power to maintain the attack in adversarial conditions.)

Attacking the network in other ways via corrupt laws with multi government cooperation would be far easier.