my church said credit cards were this prophecy from revelations
This is what I've heard too.
When credit cards came my parents told me that this has been the fulfillment of that verse. However, technology keeps on innovating day by day and the one that I believed was the microchip implanted to the wrist or forehead.
With crypto's today, it's not yet widely accepted so I doubt it.
For the mark of the beast, there's one idea that I've heard before that it was going to be another religion.
I can't imagine people implanting a chip into their forehead to spend money... that's just ridiculous
Also, the "number of the beast" (666/616) is a clear reference to Nero Caesar... they used 2 different numbers, one for the Jews and one for the Gentiles because they spelled his name slightly differently (Nero Caesar vs Neron Caesar = 616 vs 666)
So... if the "number of the beast" refers to Nero Caesar... I assume the "mark of the beast" also refers to Nero Caesar, since he is "the beast"... so, this is 2000 year old history, not a prediction of events in the 21st century