Hawala system, obviously illegal in India under PML Act but it runs well and speculations galore, it is commonly used by drug mafias, underworld bosses to run their money.
Whether they use bitcoin, possible but they dont likely use the exchanges that we use. OTC traders exist in different difficult to reach sections of the internet and they are helping such users.
Most of them have hired CAs that are well versed with all these "cat and mouse" chase methods.
Hawala system is still active in India and most friendly country for doing hawala is UAE and UK. But, I doubt a whale will be interested in using this system. As you said they have CAs to take care of the tax I still doubt they will be interested in fiat. Unless they are using the crypto market to convert black to white.
I think Hwala system is the only way of converting crypto into INR but lately there has been so many crackdowns and we are made to believe it's really difficult to do hawala but I feel it's to deceive us and I have heard from people who were once involved in this activity that the raids are pre-planned just like custom catching gold smuggling as we never heard about those who are caught in these activities after few months because they are silently released. Hawala is still very much active and also there are other ways like setting up dubious service based organisation and getting paid for service which never took place. Here the whales will be both client and service provider.
The hawala system is still active and I am sure a lot of people would be using it regularly for crypto related transactions.
Although it's a convenient way for P2P transaction but it is still very risky as it is operated very secretively.
Just imagine you get cash worth 20 lakhs, you can't count it in front of them and so you go to a secluded place or your house and then find out that the cash is fake.
You go back to the Hawala but they don't accept your fake notes. You can't go to the police since it's not legal.
What would you do in such a case ? This is something I have been wondering for a while.
This is why Hawala should be avoided as it is very risky.