I think what gave the government this courage of high tax is because they say how profitable it has been for many. Imagine somebody that has been holding Bitcoin since 2010 and are still holding it to now, that's a crazy profit one will be having and paying such will not move them if they are serious about paying the tax in the first place.
With time, if profits that are been made in crypto aren't that big like they used to be when the tax are implemented, they will have to force it down for people to play along otherwise people will be discourage from investment in crypto.
The greed of governments knows no bounds, because they also face the problem of budget overruns and are looking for new sources of revenue to continue operating. They accept crypto with the hope of more taxes from investors and the hope that the economy will have more impetus to grow. Usually, politicians who do not participate in this market as investors do not understand the suffering and hardship of investors to make profits from crypto.
If they look at the BTC price chart, as you say, they will think it's easy to hold BTC for a few years and then profit thousands of percent. They believe that investors will happily share a lot of money with the government. I think that is a misconception of those outside the market when assessing risks. Governments should also consult the opinions of those who have lost money to better understand this market, thereby making the right decisions about taxes. Ideally, crypto taxes should be as low as stock taxes.
If the government is already, as you said, experiencing budget overruns, it is certain that it will look for sources of revenue to cover all of that so that the government can run well.
So accepting crypto because of a situation like that is certainly not good for the government because it will be dependent even though it is legitimate to apply taxes to be able to be done for all those who do crypto activities.
But it must also be remembered that crypto transactions can be carried out without involving the government, and it is not impossible that crypto users will do it if there is pressure and high costs and this is a dilemma for an authoritarian government.