If the government and banks hold 90% of bitcoin then the volatility of bitcoin will become static and the value will not rise for a long time. The market forces of demand and supply determine that price of bitcoin. The government will have to spend billions or trillions of dollars to buy that amount of bitcoin so its cheaper for them to ban than to undergo such an expensive venture
There's 2 scenarios:
1. They keep the BTC in cold storage. This essentially removes 90% from the markets. With such little float, it would be incredibly simple to pump and dump bitcoin, unless it's priced at $100,000 and above
2. They do actively keep BTC in government trading accounts. This would allow any government official to conduct insider trading and enrich themselves in a day
Thankfully both scenarios are highly unlikely, governments are allergic to bitcoin