Vape shops sell addictive products and they have minimal overhead. I think the markup on a lot of what they sell, especially the more grey market stuff like nitrous oxide "whip cream chargers" and poppers, is quite high.

A lot that I see have extremely cheap-looking fixtures and little to no decor, and unlike virtually any other store, they stock what they stock, which is generally the same as every other vape shop, and don't even bother to fill out the entire space if it would hold more merchandise.

I assume some are able to negotiate lower rents in exchange for short term leases while the store is technically still on the market for a long-term lease, similar to a pop up store. A lot that I've seen could be shut down, with all the merchandise and equipment loaded into a UHaul, within a few hours if necessary.

Nail salons are similar. They really should have custom ventilation systems since they're working with paints and solvents and glues and nail drills/lathes, but this seems to not be enforced since they're seen as girly little spas rather than industrial workshops and are often staffed by poor immigrants.