Some 90% of the clothes I buy and wear now are from annual gifts of fat face vouchers and tshirts I make myself at trade cost. I have a bunch of high quality dinner shirts I've worn for years. Both my coats are from charity shops but good brands (Henri something and Next, lasted years).
For games I pretty much only buy retro or second hand from a local indie store (just one).
I do still visit the high street for small things like business stationary (card, envelopes, blah) and the occasional art book but I struggle to remember what a department store even sells or looks like. I just have almost no interest in predetermined selections, staged "offers" and suchlike. It's pretty much always gooseberry fool and feels like it wasn't worth bothering to go in.
As for the decline in the high street yup very much so, however I'm a sign maker so I literally make money with the monthly turnover of commercial property or whenever businesses change hands, meanwhile my business sells almost entirely online. I installed a fascia last November or so, it's already been bought by the nearest competitor and worked over (badly, they didn't even bother to remove my work so it still has the old new sign underneath
that would have been good for 7 years), both vape shops as it happens since that seems to be a common thing now
Shops feel they need to do everything they can to get punters noticing them, which works great for me. The ones that don't don't last very long, even the ones that do still struggle. There's loads of off (or even no) branding and bad investment in signage, some shops just look poor from the outside so I'm not surprised people aren't queuing up to purchase overpriced tat to make up for it. It's very hard and frequently premature to get a brick store up and running, and keep it running, business rates and rents are sky high. It's simply the wrong direction in so many cases to invest in premises, it's sad but it's often a stupid business decision, you get openings on the high street for people to try different things and they drop like flies. Never mind keeping up staff and payroll.
On the other hand you can get too much business online to cope with, competition is ridiculous, very unreasonable customer expectations even with the filter aspect. The logistics industry is barely functioning and the overheads there are possibly even comparable to a store. I spend a small fortune on shipping, but prices are quite good for that because there is so much competition there too.
I think smart businesses will operate on a small service area, local level with generous prices (by that I mean not too expensive too too cheap) and robust online infrastructure, things can actually be very good for new business provided your product isn't two a penny. Compete on quality and brand and unique options. trouble is a lot of high street stores just deal in the same gooseberry fool as everyone else so have no reason to exist. Then you can franchise out or open in other locations or just focus entirely online once brand is establish (should send commerce both ways). If that's the way things are going it doesn't make business sense to work against it. Obviously there are some industries like clothing and food etc that will always have a high street presence by they need to do a lot more for example have integrated online experiences with loyalty schemes and same day collections, online discounts etc and a very strong social media presence. The events industry is seeing a massive boom because shoppers want experiences not just doing the same thing they can do whenever they want but more expensive and more hassle.
Basically the way money and commerce works now the answer for most businesspeople as to whether you should need or want a shop the answer is "no". As a society we need more community centres and more accessible technology for the young and elderly with skills and plant decentralised to create a boom of community plus competitive service offerings from many individuals and small groups, not just how many shop windows you can cram into a road. The only function there is a till and (often poor) 121 service and displays. It really is archaic.