It's should be like that, when a successful investor or someone who sells bitcoin into local currency should be taxed. Because if not like that their country will experience an economic crisis and even go bankrupt.
Obviously in the future surely the popularity of bitcoin will be lower, because in addition to successful investors there are also small people who are trying to get very low amounts of bitcoin. Maybe for successful investors this don't affect his business, because I am sure they make quite a lot of profits
There are already thousands of other taxes and now bitcoin tax. It is not good. I was happy that cryptocurrency is decentralized and there are no taxes on it but now you are telling about the tax. It means that the income of bitcoin will also reduce due to impose of tax. I think only those countries should collect tax in which crypto is legal and people trade and invest in it openly.