For example at this link https://www.thesun.co.uk/tech/5092224/criminals-use-bitcoin-for-dark-web-illegal-activity/amp/.
So if there is nothing correct regulations, maybe a lot of countries will be block this payment system.
And as the effects, price of BTC will be drop soon.
So let's start to discuss, what it the right regulations to avoid Bitcoin used as a payment for crime
I will provide conclusions intended by OP, many people used bitcoin as an illegal transaction so as it will make the government worried to adopt bitcoin as a payment system.
This case is often discussed in this forum, the government wants a secure payment system. There is no negative element to the payment system, while bitcoin which has a decentralized system and every bitcoin user is free to falsify their identity to create a wallet, so the government will find it difficult to track down users who are using illegal transactions using bitcoin, even though this case would be the same if someone did illegal transactions using money fiat, but at least this case will be used by the government as an excuse to not adopting bitcoin in their country.