I have an elderly family member with this exact problem. Even with constant reminding, it is an uphill battle. I suspect it is a combination of addiction but also "dark patterns" that essentially trick folks into spending money.

One thing that helped is switching the family member to a True Link card: https://en.wikipedia.org/wiki/True_Link

While not perfect, it does root out the obvious scammers and does make it much easier to push back and cancel those reccuring subscriptions that "some how" keep getting activated.

I have no affiliation with True Link, but posting it in hopes it can help someone with a similar problem.

Edit: Just now realized True Link has a YC affiliation, so maybe this is more on topic than I thought.