This occurs in all sectors, not just gambling, but also in matters related to finance. For example, most people now shop online, and the rapid growth of online stores is evidence that the internet is truly shifting the market.
When it comes to gambling, I personally find it more comfortable and, of course, easier when playing at online casinos, because I can gamble anywhere and anytime, as long as I have the money and a reliable internet connection. However, there are both negative and positive sides, although both sides will always be present in any situation, as long as we are not mature in our responses.
It also in theory makes it cheaper for casinos to operate - they don't have to pay for expensive physical buildings with all the taxes, upkeep, staff, maintenance and security comes with it. Sure they might pay for staff and security in a different form online, but it's a different set of rules. This allows them to run more efficiently with their major overhead becoming advertising spend so people can find them. Once they grow big enough they can cut back their ads and start to offer a few more perks to customers. They do have to pay a lot of money to make sure hackers cannot get in, especially with crypto because they have to defend their hot and cold wallets - if that money gets taken there is no route for a bank to recall it.
I can't say much about the cost comparison between brick-and-mortar and online casinos, but they might be able to cut costs on space, such as buildings and other physical equipment.
However, in terms of security, I think online casinos need to go the extra mile, as the digital world is now incredibly dangerous for malicious individuals. Therefore, they must ensure they have a security system that cannot be easily hacked by thieves.
