Online casinos offer many benefits such as privacy and convenience. They singled out LGBT people but this is probably the preferred option for the general population as well.
Agreed, in the study mentioned by @noormcs5 conducted by Dr Reece Bush-Evans and YGAM, they didn't mention the sample from the population as a whole so we don't know whether this research was conducted in groups with large populations or not.
I have read the article and the article states that " 71% of the interviewed LGBTQ+ adults admitted that they had experienced some form of discrimination or harassment in their life " and not in the casino . Where's the percentage of LGBTQ+ who prefer to gamble online rather than going to a casino? nothing, so, we can conclude that people prefer to play at online casinos because of the convenience it offers.