If I should ask "What do you mean by to support Bitcoin?" Or are you referring to legalizing it as it's been done in some countries (e.g El Salvador & Central African Republic), because if that's the case & what you are referring to then I think you just need to understand that the fact that BTC is not legalized in a country, it doesn't mean it's prohibited or a crime for someone to buy or invest in it as an alternative asset for the future. And as such, there are some people who still own Bitcoin in a non-Bitcoin environment through the help of p2p, which anybody can use same medium to get their first BTC
That's the problem with the post, the OP was not clear. Support for Bitcoin can be categorized into different sections.
Legal tender:There is just one country where Bitcoin is a legal tender which is El Salvador. Central African Republic has repelled the law that made Bitcoin a legal tender in the country. While in some nations Bitcoin is a currency and not a legal tender. As a legal tender individuals and corporations are mandated by the law to accept Bitcoin. So nobody has the right to reject it as a means of payment.
Currency: You can use Bitcoin freely in places like Hong Kong and Dubai because the law fully supports it. Bitcoin is a recognized medium of payment. Banks and other institutions can pay and receive Bitcoin from customers. As a currency it not compulsory that it must be accepted by any individual or institutions except it is backed a law or agreed by both parties.
Partial Ban: Some countries have laws that ban or place restrictions on Bitcoin but they are hardly enforced. In such countries, you are free to engage in Bitcoin without any restrictions. Also, some countries have no policy on cryptocurrencies, one is also free to use Bitcoin in those countries. In some countries like Nigeria, only banks are restricted from engaging in Bitcoin transactions so citizens and companies can freely use the coin.
Strict ban: Some countries like China enforce the ban on Bitcoin and violators can be persecuted. In some countries investing, trading, or using Bitcoin is a criminal offense that can attract a fine or imprisonment.
Tax friendly/unfriendly : There are also nations that are tax-friendly to Bitcoin while others are hostile. In many nations, you will just have to pay little or sometimes no tax on income from Bitcoin but some tax it heavily. Germany, Singapore, and Hong Kong have lenient crypto tax laws.
Mining friendly/unfriendly :We can also have another two categories which are nations that have banned Bitcoin mining and others that are not hostile to miners. The United States of America is mining-friendly.