While I think the comic is very humorous and does have some truth in it, I feel the real reason is somewhat different. Banks are threatened by Bitcoin and they should be. I have no idea how many people would use credit cards to buy Bitcoin at all time highs but I don't think the number is all that great. But...Bitcoin is at a cross roads. It has gotten a ton of press and it could go to the moon or with the help of big business and the media they control it could be brought to it's knees. While the mainstream may be saying the bubble has popped, the crypto community is hodling and calling this a "health correction" and a once in a lifetime sale. "Before the institutional money comes in".

So we have a situation where there are many true believers who are currently "all in", which means they are basically short of fiat. They are going into despair because they know 10x gains are real because they have experienced them. For many of them the debate is whether Bitcoin will go to 30k or 300K. The lower the price goes, the more desperate they become. They may currently be sitting on a lot of crypto wealth even in this bear market so they feel they have cushion and collateral. So why would they not max out their cards?

If the banks were to allow credit card purchases, they would probably give the market the liquidity and stimulus it needs to get through this rough time. That would mean that the last great hope to "kill the beast of Bitcoin" would be lost. On the other hand, should it not be enough and Bitcoin goes to 1K, then they are sitting on a lot of bad debt. Not the small amount that newbies might have put in just before 19k top, but large amounts put in by people who are true believers.

Either way the banks lose.