When we talk about legalization of cryptocurrencies across the world, it is yet to be confirmed that all countries will be able to adapt to its usage. All of them have their own issues in regards to the currency use. I believe its not possible for cryptocurrency to become completely legalized worldwide, considering its current position in the market.
of course not all countries legalize bitcoin because every country has different laws and rules, maybe in some countries will legalize because it sees profit factor but some others may be banned or let them, for the moment that is what happen, in the future? maybe the situation will be different, see we will meet the era of more sophisticated technology
It may come as a snowball effect when some countries take a judgement from another country as a pattern to follow. Or it may be that a cluster of countries like EU adopt a law that is valid in all the members of that union. For example: German Federal Ministry of Finance announced that purchases of bitcoins would not be taxed, as the cryptocurrency is a legitimate payment instrument. The Office issued its decision on 27 February. In this document, the regulator relies on the Court of Justice of the European Union in 2015. And this ruling sets a precedent for all EU members.