I enjoy playing summoners war, but recognize it as basically a slot machine. There are people on there who clearly have spent a LOT of money. I've chatted with a few of them (the largest that someone admitted to was $5,000), and most of them claimed to be well-off enough that it wasn't an issue. One claimed to be the son of a successful investment banker. One was from China and said he doesn't even know how much money they have, but they always have plenty. Nobody I talked with has been all like, "yeah, i am hurting myself and racking up debt, but I just can't stop"
Of course, if you assume even half of those people are lying, that's where the addiction is. You'll tell yourself stories and tell others stories, so they don't see you as a weak person.
They even use casino terminology , bucketing their users into minnows , whales and what not.
For free to play games most users spend almost nothing. But there are these users that spends thousands of dollars on the game as if it were nothing.