BTC is not a good crypto, but is the one that appeared first.
So it is the "gold standard". It is terrible for transactions, but can be used as a reserve, the same way gold can. Also, moving gold arround is quite expensive, so people just move certificates, mostly.. someone is keeping it for you, even between countries: same can be done with wallets.
The main reason governments don't like cryto is not privacy. Nothing less private than a public ledger! The reason is governments print money. Literally take cloth/plastic and make money, with little cost. On top of that,. using interest rates they control monetary scarcity/supply.
If other people essentially start "minting coin", this takes one of the main sources of power out of the government.. and it is the government/mps/etc who create laws and control the economy.. they won't allow other orgs to do so.
Are there tulip runs with cryto? of course.
Is it private? no, it is the opposite of private, it is PUBLIC.
Also, the economy is waking up and electricty is needed, so another reason not to allow serfs to mint coins.