There are several cons as 30% is a big share.
Is there any possible way to legally avoid the taxations?
There is no way you are going to avoid the taxes living in India and using the exchanges situated in India. The possible way is that you can move out of the country to free heaven like UAE or other similar countries if you are dealing in huge number of coins and become an NRI and you will get an tax exemption .
It only makes sense if you are holding millions of dollars worth of cryptocurrency.
