Sir, Crypto is stupid when it comes to transactions. Because it doesn't differentiate between a 1Rs transaction vs 1Crore Rs worth transaction. It treats both as the same, needs the entire Blockchain to authenticate both and requires the same effort, energy and latency to get settled. That is the big drawback.
If I am paying you 20Rs, its inconsequential, but if I pay you 5Cr, I would want the bank to OTP the shit out of me, get their local branch manager to be physically present, need the super expensive stamp paper and the entire presence of 2-3 regulators to oversee so that either of you and me doesn't back out.
What's money transactions anyway? Transferring a store of value that the society has from one to the other. Fiat does it better than Crypto due to sheer customisation of the process.