I hope one day I'll be able to play it normally, but I'm not sure. So yeah definitely it can "cost" a lot to play.
I seem to have addictive tendencies, but there's a whole multi-dimensional spectrum, as far as I can tell. In my case, when I'm working overtime, I'll jump into a game every few hours for 30-60min just to let some of the stress off. It's quite effective, but I end up popping figurative gaming-pills instead of learning to deal with stress in a constructive way. I'll also do something like that after a tiring day. It's not good, because it's grown into an urge that I get when it's time to relax, so I neglect other parts of life to which I'd ideally dedicate that free time.
It's an endless treadmill with diminishing returns. It's full of (digital, ultimately meaningless) rewards which make you stand out above the rest of the players. Some of them are worthless in a few weeks/months (e.g. gear), some of it is timeless (e.g. mounts) but takes 100's of tries (every try 30-60 min) for that 1-5% chance to some mount.
When I played the game, there were people who did nothing all Wednesday (when they could try again for the week) but running hours and hours of dungeons just so they could have a change to get the last 10-100 rare mounts they missed.
The highest-tier end-game content requires large groups (20 players + reserves) to coordinate schedules and tackle dungeons together. This causes enormous social pressure to keep showing up because otherwise the group can't play the game and everyone is mad at you.
It's perfectly possible to play it casually without participating in the above, but it's a game that has a lot of traps for people prone to addiction to fall into.
So one main for solo content of the week and then back to leveling alts.
And then Legion with the content that was specific to each class. Loved that idea, but it really made you feel like you were missing out if you didn't have x class to see something.
If FFXI's leveling wasn't so group focused and slow, I'd probably love that system above anyone else: I do like the idea of needing to level various classes, but I'd prefer it be all on one character instead of 12 or so I need to manage.
Wouldn't FFXIV fit the bill?
I'd prefer the job system where you switch to ClassB, but have to level accordingly. I'd hate to be max level of ClassA and then want to try another class and out level content to really practice the class properly (or be swamped with skills early) or end up being unable to help a group because skill in another class is inadequate.
So basically, FFXI but with soloable leveling (in FFXI apparently you could solo with beastmastery or something as a subclass, pet tanking I believe, but it wasn't a starting class so you'd have to work to get it).
So my problem was that gaming was winning over other things all the time on almost every occasion. I was evading responsibilities at home, neglecting my relation with my wife and not giving quality time to my daughter.
So now I'm like 3 months free of gaming and while being hard , I can now see I was using it not for the right reason.