That is not the message we are putting across, we are giving our customers the ability to take control of their own money, they do not have to convert back to EUR to spend their money.
I was referring specifically to the message they'll get when looking at the security of their euro-denominated deposits. I don't dispute there are benefits in other areas - but the most critical one with deposits of any kind is knowing that they won't vanish/devalue.
Let me also explain why having your own exchange-rate that lags behind the market won't work : as you don't appear to have grasped the problem. I'll use an example of BTC halving vs Euro in a short time-frame : remember that on the recent bubble (and on previous ones) it actually fell by a lot more than 50%.
BTC has bubbled up nicely and your internal rate is at 200 euros per BTC (other exchange-rates have gone higher but you haven't caught up - which adds a seperate problem that I won't bother discussing).
BTC then crashes to 100 euros per BTC.
With your 30-day average your rate only drops to 190 euros per BTC (obviously your buy and sell spread are either side of that).
Problem is that you accept BTC deposits. If your rate doesn't also drop to around 100 euros per BTC then people can:
Buy BTC elsewhere
Deposit them with you into a BTC-denominated account
Withdraw from that account in euros - either in cash if allowed or if not via purchasing with your cards.
There's plenty of ways to convert cash on a card into physical cash/cash in a bank account - most have costs associated with them but with an 80%+ profit margin those aren't going to be much of a barrier. Most of your merchants are going to want euros not BTC so you''re left with the problem of internally valuing BTC at 190 but having to settle them when you can only get 100 for them on the open market. And that cash isn't going to just cycle through once - anyone who spots the opportunity is going to shovel as much cash as they can through it.
And then when BTC finally rises back elsewhere, your rate is going to lag behind on the climb again - at which stage they can deposit the last batch of euros with you into a BTC-denominated account then withdraw the BTC as BTC.
There's no way around it unless you either:
a) Run a MASSIVE spread - which would discredit you immediately (can you even imagine the response if you gave one rate on deposit and a rate that was 50% worse on purchases?)
b) Disable transactions in one direction after large-scale currency moves - i.e. not just put your own head in the sand put force all your customers heads in there too.
c) Forget the stupid idea of having a pretend exchange-rate and stay fairly close to market rates.
Problem with c) is, of course, that you then need heavy-duty hedging in place. And that costs a lot and isn't very easy to do - in part because noone else is doing it extensively so there's noone supplying the facility at reasonable rates and high volume.
I guess there's theoretically an option d) which is that you don't publish rates at all and people just have to accept whatever you give them - but that's like option a) just worse as far as credibility is concerned.
Now you can MAYBE bluff your way through with most people - but it doesn't need too many understanding the problem for there to be a run on euro withdrawals any time BTC falls significantly. As if your disclosed strategies are no more than "we'll hedge but we haven't disclosed how and there's no provision in our accounts for any costs of hedging" then noone with any sense is going to leave euro-denominated deposits with you backed by BTC with a lower market value than the euros if they can just withdraw the euros into cash. And even a small run on euro-withdrawals makes the situation much worse - as in the process of filling those you reduce the BTC/euro cover for the rest.
Your idea of time-locked deposits that pay a percentage of the increase in BTC's price is interesting on the face of it however:
1. If you're guaranteeing no loss (or, worse, guaranteeing a minimum return) then it means you have to hedge even more efficiently (as by giving away part of the gain when it rises you have less surplus from that to hedge with against any fall).
2. If losses are passed on then rather obviously they'd be better off just buying BTC themself and keeping ALL the gain and none of the CP risk. Think even the really stupid ones would spot that. As they can't spend it none of the other benefits apply to mitigate.
It also follows from 1. that if they get a percentage of gains then you must have a transparent means by which your rates are set based on third-party sources. You can't be making them up yourself arbitrarily if you're paying variable interest on deposits based on those rates. Which totally limits your flexibility in terms of the burying-head-in-sand strategy.
