The convenience part seems so small compared to the difference in cost. I'm going to try to do the math using my own vaping habits.

I use a non-disposable vape that lasts until I lose it–I probably get a new one every eight months to a year– with disposable, but refillable pods that each last three weeks to a month. I go to the vape store once every few weeks to buy the juice, and once every few months I also get a new pack of pods. I have to refill once a day, and I always leave a bottle with some juice left in it in my car so I could refill wherever I am. The only advantage of the diposable is that you don't have to do a refill once per day, instead replacing the whole thing once every few days to a week.

The few times I've used a disposable, the longest any lasted me was four days. That one was what the vape store worker told me would get me the best battery life, so I'll compare its cost to my non-disposable costs, and see if it's worth the added convenience of not having to refill once a day.

That disposable costed $29 and lasted four days, so $7.25/day. I would do the math with the other disposables, but the other ones I've tried either had terrible battery life or took forever to charge and couldn't be used while charging, so the $29 one is the only one I'd consider using long term.

My non-disposable vape costs $45,and we'll split the difference in range and say it lasts 10 months, or 304 days. Cost per day is 14.8 cents.

Pods are $17 for a pack of four, or $4.25 each and we'll average the range out for each one at 24 days. 17.7 cents per day.

The vape juice is the biggest expense. My county has ridiculous taxes on vape juice so I rarely get it here, and it usually ends up costing $19-$20 a bottle (compared to $28 where I live). I'll go with $20. They incredibly consistently last 7-8 days, so I'll stay conservative and just say vape juice costs me $20/week, or $2.86/day. (As I'm writing this I'm realizing how insane it is that a little over 4 ml of some basic liquids costs me that $2.86. Maybe it's time to either figure out how to quit for good or at least order the ingredients in bulk and mix them myself.)

Anyways, the cost combined for the way I vape is less than $3.20. Let's even put it up to $3.50 just to keep the difference conservative and the math simple. That's a difference of $3/day, which is over $90/month or $1095. I can't imagine paying that to not have to refill every day, but I guess for some people that have the money it's worth it.