i think bitcoin itself cannot be tax, i cant think of a way how to tax it, the only way that the government tax the crypto is through centralized exchange and merchants that accepts bitcoin or altcoins.
I think you are confusing the government's ability to tax bitcoin with the requirement to pay taxes on bitcoin. The government certainly is at a massive disadvantage when it comes to determining the accuracy of an individuals tax filings when it comes to bitcoin. Just because the government is not able to easily hold us accountable, does not mean that taxes simply do not have to be paid.
Bitcoin is still a capital asset. If income is made in the form of bitcoin, it still needs to be taxed as income. If an individual makes a realized gain from the sale of their bitcoin, then that profit is subject to taxation as well.
If an individual avoids paying taxes on their Bitcoin, they are going to run into troubles whenever they try and spend it. Most legitimate exchanges will report large transactions to the IRS. If you accept large payments in exchange for your Bitcoin, the IRS will be able to track that. If you do not pay taxes you will not be able to make any large purchases without the IRS being able to determine you are committing tax fraud.