Maybe all will differ on current situation of the market since majority will use bitcoin to gamble when the volatility of this coin became stable and no losing in value due to crash has been encounter by a user. We or other decide to use alts when bitcoin is doing some crazy actions and people cannot afford to spend their bitcoins that's why they look for alternative coins so that there hodl bitcoin will never get touch then be use for what they think much better way to earn more either trading it or just simply wait for the price to soar high.
From what I see, regardless of the BTC volatility and high-fee-related issues, gamblers will still be gamblers.
We don't even see a noticeable decrease in gambling activity, at least in crypto-gambling platforms using BTC deposits even recently, there's a high fee related to any BTC transactions. I don't really see that most gamblers really care about that as long as they can gamble. Alright, let's say they care for fees, they will just use coins that have low transaction fees but it doesn't mean they use that coin because that's their preference to use.
Aside from that, nothing really changes on the winning rate regardless of the coins used. For a much more convenient gambling experience, at least in my case, I like to show my balance in fiat value so that I know how much I'm putting into to any bet regardless of the exchange rates.
I personally stop gambling the time when the transaction fee is insanely high. It cost 15$ for transferring funds in a slow mode which is troublesome for a small-time gambler like me. I think the high fee recently affects small-time gamblers and those who withdraw funds from their casino balance. Whales are probably not affected by this since it's a one-time payment and it's nothing compared to their huge balance.
What are you using to get the statistics on how the activity of gamblers doesn't change on a specific time? I'm interested to have a data analysis on the gambler's behaviour during high fees or crypto market dumping/pumping.