People buy luxury goods for all kind of reasons. For you, it's quality. For others, it would be association of luxury lifestyle/ to show off. With Instagram, many millennial buy luxury bags so they want to come off as wealthy so they can gain followers. Then in turn, these millennial influencers can get sponsors to give them money so they can spend that money as they please. The point I'm making is people buy these luxury bags for all kinds of reasons and I'm sure there are other reasons why people buy them besides the few I listed.
Luxury have always touted itself as quality. Sometimes that is true. Sometimes it's not IMO. LV actually makes pretty good quality bags. They often stand behind their bags as you can return them most of the time if there is obvious quality problems. They recall bags if certain style becomes too problematic due to whatever reasons. You can also bring your older bags to have them fix them at a cost/ or sometimes free. Try that with most brands and they definitely don't do that. All of these comes with added cost which is priced into buying a LV bag. Surly you have bought stuff from H&M before. I can assure you H&M isn't likely to take any hand bags back after 30 days and I would challenge you to find any H&M bag that last as long as LV bags.
LV wants two types of consumers imo. One type is who can go into LV and buy anything they want. They don't have to save up. Those ones are obviously in the minority and LVMH will not have the numbers they have if they only cater to that type of customers. I would bet majority of the customers at LVMH buys maybe one or two bags a year. Those are the ones who you see post here quite often saying they have speedy, neverfull, toiletry pouch, key pouch, etc. that saved on their online favorite tab. These people are bread and butter for LVMH. At the end of the day, there are only hand full of people who can buy multiple LV bags at once. In order for LVMH to make their number, they have to cater to general public instead of just to ultra rich.
Judging from the number of posts under LV tab (compare to Chanel, Dior, Hermes, Coach, etc.), I'm pretty sure LVMH has succeeded in their strategy.