Simply put, they don't want their users see any bigger profits than their existing investment products can give.
Those, typically funds of funds with sky-high management fees and hidden costs are pretty laughable once you know what to compare to. Still, they're the product banks have the highest profit margins on. Those margins gotta be defended at any cost.
Some more modern banks allow individual stock portfolios, but still, with extreme costs related to a broker. I'm talking about 10 USD plus 0.3 to 1% trading and currency conversion fee for example. (I'm from Europe, this is pretty much the standard pricing here)
Imagine, banks would introduce in-house cryptocurrencies with similar trading fees. Maybe drop the fix trade fee, keep the percentages, even 1% is 100 times worse than an average crypto exchange. Crypto users are not accustomed to these rip-offs, and banks will never be willing to drop down to 0.01%, I can assure you
Banks are profit machines designed to take your money, not make it.
don't say that but their people who are profiting from the banks, but I can only support you is that banks won't want to approve crypto currency to link up with them. Cause they know more of the profit will surely go to Bitcoin on the process and much customers will likes to trade with Bitcoin, one thing is that the government have already seen where it's heading and they're afraid that if they regulate crypto currency and approves it with the central banks. Their will be lose to them but for my opinion that's the more profitable the government will surely have, okay for an example if the banks are paying tax like 2.0% then definitely crypto currency will pay more than that because they have more source then the banks. Maybe they might be paying like 6.0% in this case the government are profiting from both but they are scared of fraud or scams, just because of their so much platforms and investors everywhere.
On addition...
Come to think that if people would be having that enough income or profits then there's no one would really be trying out to get those loans and amortizations on which banks offering, on which means that
it would be a less revenue or money making for them. Also, banks are institutions which are highly regulated by the government. If on what government hates, then they would definitely be hating it too.
Here in our country on which it is really that a bit shocking or surprising that there are banks offering or allowing crypto transactions or even allows incoming or outgoing transactions without questions asked
but just as expected on the moment that you would be able to hit up those threshold then you would really be that definitely be ending up on being asked on why it is really that too big.
Where it do came from? DANG, it was a trap then those funds are locked.
This is why its not really surprising that they would really be hating crypto that much. There's no way that they could control people about their funds and with having that full transparency
on which know that this is something that where crypto is really known for and been much supported. Government doesnt really like crypto no matter what
since it is really that against on what they do like on which on having that full control which it would be understandable.