Yes, online gambling is more prone to addiction because of the ease of access. You can play literally anywhere. It can be accessed through a smartphone and you can play anywhere you go with just the internet as your weapon and some cryptocurrency as your betting option. It doesn't need to be hard cash which also makes it easier for people to gamble. One bank account can also make it possible and considering how credit cards have triumphed over the financial industry, gamblers could use that as their means to gamble more.
Also, you can do it at ease at home and you don't even need to dress up and make an effort to go to a physical casino. The only good thing about being in a casino is the fun of being around gamblers and players. But for a person who has been gambling for a long time, I don't they will mind that. They'd probably would rather be alone in their room than be on a physical gambling site and it makes not much of a difference.