Prudent and Bitcoin are two words that don't belong in the same sentence. You never know when and if you're in a bubble until its too late, but the ludicrous growth isn't a good sign of stability.
Either way, the "correct" way to spend BTC/ETH doesn't seem to be via a series of transactions made via a VISA, does it? Why would go not go directly via an exchange?
How does selling at an exchange, eating a 1.5% fee, waiting 4-5 business days for your ACH transfer to clear, then using that money in the bank to send a payment to pay a normal credit card bill get you want you want faster, easier and cheaper?
With this, you can escape large parts of the banking system and control more of your own money in a more granular way if you choose to.
"The Visa card, which will be issued by Gibraltar-based pre-paid card provider Wavecrest, will be linked to an app that allows users to buy and hold cryptocurrencies through the LBX exchange. Customers will also be able to withdraw money using the card. Cryptocurrencies will be converted to sterling at the time of withdrawal."
Great, so I can put in £200 at the start of the day before work, then when it gets to lunch and the bitcoin market is currently crashing, I can withdraw my full savings now valued at £2 and buy half a sandwich, bargain!
But really, if you are at all worried about losing all your money in crypto, then you should only invest a little, and..
sell 50% once you 2x..
or sell 20% once you 5x...
depending on how worried/patient you are.
or any combination you're comfortable with so that losing "1x" will not put you worse than you started.
Can't afford a whole bitcoin? Buy a half, or a quarter, or an eigth and apply the same strategy..
Yeah, of course it could go to zero before you gain, but really, it's not looking like it. There has not been a better investment opportunity in our lifetime as what we're seeing now.
I think it's crazy that so many people who know about it are still hesitant to put even a modest amount in for fun.