You posted that in Islamic religion, gambling and betting are seen as Haram. Gambling sites also know this and they avoid to relate with Muslim's festive celebrations. Or am I not getting it right? I have not noticed anything like that before.
Christmas and the Easter celebrations are symbolic for the birth and death of Christ, the Casino's know this, and are also aware that gambling is a sin in the religion of Christians, but they still do not fail to bring up Christmas and Easter events. Are you saying that Casino's are religion sensitive?
No, it's simply because casinos understand who are their target audience among the different religions we have in this world, and as such organized events to sort and entertain their respective audience for profit maximization. Because one thing you just need to understand is that casinos are not Charitable organizations, but rather a profit oriented entity who goes about launching events that will yield massive profit, which is why casinos mostly invest in Christmas and Easter events, knowing fully well that majority of their gamblers are Christians, who do not dislike gambling and see it as sin, just the same exact same way the Muslim does.
Hence, as you kick-start in your Ramadan fasting, it's advisable you keep the fasting holiday secred.