it's fear basically, all these governments are afraid that BTC will take over and no one will trade their useless FIAT printed money. It kinda makes sense for regulators to be afraid with it, because they use money to basically adjust the economy, they can print more money and bring more cash to circulation to adjust inflation/deflation, and with Bitcoin they don't have these kind of options, because Bitcoin is decentralized and generally can't be adjusted (the supply is limited). There is a good chance that governments will issue their own cryptocurrencies, but adopting BTC is something that we will never happen, maybe they will legalize it but it will never replace the government issued money (most likely it will just change form, it will become digital money/crypto coin - but still controlled by the government).