The thing is, India are known for corruption in their government and they use the current Banking system and cash as a tool to hide their corruption. A technology like Bitcoin with a transparent Blockchain will make it more difficult for them to hide corruption and they obviously know that.
I'm from India as well, I'm not offended by your words but let me remind you that most of the Govs in each country are there to fill their own pockets. Indian Gov is not just using cash and Banks here, but they are putting their "black money" outside the country (mostly in "SWISS" Banks) in order to remain safe if a raid gets conducted at their premises and they are even using crypto themselves for the same money-hiding (or I should say money-laundering) purpose. It's not hidden that most of the politicians (whether corrupt or not) are involved in cryptocurrency investments themselves, or just think as to what is stopping them from banning crypto here? They're now playing positive and coming up with some possible regulations (but fuck regulations, I'm loving Bitcoin the way it is now).
They are also in control of the money supply of their local reserve currency, so manipulation of the value of the reserve currency will be undermined if Bitcoin is allowed to flourish.
How exactly can that be the scenario?
Did US lose after allowing its citizens to use BTC? Nope, it's gaining only in its value. I don't understand what makes them think that use of Bitcoins would either destabilize or narrow down the value of the major (reserve) currency when, if used properly and gained more in proportion to other countries, can only let the local currency shine. I don't think Bitcoin is too big yet to make such disastrous harms to our local reserve currency and it really needs an extremely huge market cap for that to happen.
It has nothing to do with terrorist funding and money laundering, that is just smoke and mirrors.

They're just adding more stuff like those heavyweight words in order to scare their people to stop using it or show up with all the transactions, pay taxes and be their puppet by showing all the info and finances we do, or else get fucked by them by being sent into jail.
@OP,
For your kind information, the image you used has nothing to do with crypto as he was Datta Phuge (Gold Man of India) who (lived in &) was killed in Pune for his love and devotion towards Gold.