We are not in the 90 anymore.
So, right now every business scheme is more popular on online. It's not only effected casino but also other sector as well we are in the generation while everything can be access by online.
So, landbase casino right now is quite need to adjust for the change,
I think the comparison is about online casino usage between Fiat and Crypto but sadly @OP only present a USD usage compared to crypto usage which is very biased since the terms was fiat currency that includes all other fiat currencies. Looking at the USD usage and the cryptocurrency usage in online gambling, it is clear that fiat currency is still leading in terms of casino usage.
I don't think cryptocurrency gambling usage is more popular than the fiat currency. Online casino had been using fiat currency for deposits ever since it was established so it is very impossible for cryptocurrency to out perform it in a short period of time terms of online gambling usage.
Crypto-based casinos have been ruling fiat-based casinos for a long few years now, in fact, fiat-based casinos are shifting or adopting cryptocurrency, they have to because players are now moving to Crypto based casinos for better experience and convenience, and privacy protection, something fiat-based casinos cannot offer.
This trend is going to be permanent and the time will come there will be few fiat-based casinos, players are using Bitcoin BCH and Ethereum because this is the most popular coin in the community, its a currency of choice, and because Bitcoin is the top coin, and it will remain this way for many years.
I think otherwise, fiat currency online casino is adopting cryptocurrency because there is a new set of client packaged with it. It is not because cryptocurrency is outperforming fiat currency but it is all about adding more audience to their platform.