If you have access to the Internet and a Bitcoin wallet, you can invest in buying Bitcoin.
But you need fiat to buy Bitcoin, this is part where government could interfere people from buy/sell Bitcoin.
I agree with you. To deposit and withdraw our Bitcoin on exchanges, we need fiats and bank services. If the government bans it, we will have difficulties in depositing and withdraw on the exchanges. Although we can get Bitcoin from bounties and trade it on exchanges, there should be time to convert Bitcoin to fiats. So, actually, we also need the government to allow Bitcoin investment.