Of course the use of bankroll on a casino page will definitely attract gamblers into venturing the games and gambling activities they have to offer. The fancier the bank roll the more customers are attracted to them in some cases. However aside the bank roll stuff, a good reputation has a strong role to play in how incoming gamblers view a casino. Even if the casino uses a very fancy bankroll to draw gamblers attention, the whole scheme will eventually fade off if they are not able to perform properly is a similar manner the information the bank roll is trying to pass and this could eventually make them lose customers.
Displaying their bankroll is not a very necessary thing as some persons are not moved by them especially because these day some casinos fake bankrolls just to get a bulk audience.
In the early days of crypto gambling, I understood that we used to ask the bankroll of the casino just to know if the casino has the capability to pay winnings or not. But these days, I don't think it is necessary as there are measures that you can check if the casino is capable of paying their players or not.
And as you mentioned, about faking bankrolls. That is true, can we really get the actual numbers in case casinos make their bankrolls public? I don't think so. Instead, we can look for other aspects that can manifest that the casino is doing good in terms of their finances, such as -
> no withdrawal complaints
> fast withdrawal or no delayed payments
> can afford to release big winnings in a timely manner
> can run high stake contests
> can afford to pay popular celebrities or personalities as Ambassadors of their site