it is difficult to regulate BTC because from the start BTC has been designated as a decentralized currency, and transparent in its management, but with a centralized platform owned by governments or individuals that can be regulated as said, using fiat currency as a means of illustration
Exactly. You can't regulate something that's decentralized. That's because network participants are spread across many regions around the world. If one country decides to "ban" the usage of Bitcoin, miners and/or node operators from other countries will continue to support the Blockchain. Crypto-friendly regulations will only encourage the growth of Bitcoin within a specified region. When there's a "full blanket ban", Bitcoin's growth will diminish. But that doesn't mean the cryptocurrency itself will die. People will find other ways to circumvent government restrictions in order to get access to Bitcoin.
For Bitcoin to go down, the whole Internet needs to be shut down (something which is impossible). Governments will only be able to regulate centralized exchanges since these are concentrated within a single region. But they won't be able to regulate decentralized exchanges, and even in-person trades because of the reasons mentioned before. Things will stay that way as long as Bitcoin remains decentralized and censorship-resistant. Just my thoughts