Its all about control. Any government would love to have absolute control over its citizens. A controlled citizenry is every government dream. While the government, having little or no control over its citizens use and adoption of bitcoin gets them scared.
It goes one step further in addition to that. The individuals inside and close to the government are profiting from the fiat shitshow personally. So its not just about control, but also about their current and future wealth. Fiat guarantees them steady power and wealth without the hassle of needing to earn it on a fair playing field. Bitcoin would end this party and no one inside these circles would like that. Their life's would become worse, theres just disadvantages for them by adopting it. So change will likely come from the bottom up, the people and governments most disadvantaged by fiat will adopt it first as theyre the ones benefiting from having a fair playing field again.