One way to run a zero edge gambling site would be to put a lot of Ads on the website. But who would want to play on a casino where constantly pop ups come up and you see Ads in every corner of the monitor.
I think it's better for a casino to have their edge in the games so make at least some money, as they have quite a few expenses, like servers, security, coding, support, etc.
We all want our crypto casinos in good financial situation and not going bankrupt.
We dont want to see the ads on the gambling sites. Also the revenue generated from the ads will not be that much as compare to how much a player may win from a 0% house edge casino.
In the long run, any site which has house edge will always win. In the short term, it doesn't matter however because the chances to win are almost equal to 50% so the minor volatility in luck doesn't matter in short term of the house edge. However if there was no house edge, all casinos would go bankrupt as any lucky player would just win so much.
No gambling casino can run successfully without a house-edge. Those who claim that they are running with zero house-edge are speaking false. Don't trust them for this.