I certainly don't use the 'best' of everything, but there are definitely some places where I would justify spending the money.
Most involve the contact points.
That's an interesting one because in most aspects I do behave exactly the opposite of you.
Possibly as there is a remarkable difference in behaviour in between different countries - you are in the UK and especially in London while I am in Germany and there in Berlin - so we both are cycling the capitals of our country.
Gloves: I don't use gloves for everyday biking. I may use cycling gloves on longer tours (maybe >70km), but only sometimes. I do use gloves in winter but just because of the cold and the wet. Instead I use Ergon grips (cork version).
Shorts: I don't use cycling shorts/bib tights/padded shorts in my everyday riding. Again I may use them on longer tours but again only sometimes.
Jacket: I don't use high-viz at all apart from my rain poncho from Carradice that is high viz. There is no other color available anyway and in the rain it may add a little bit of awareness in bad conditions. I would recommend this poncho as a very good piece of kit on the Brompton btw.. I consider purposeful high viz clothing while cycling a bit bringing you into a self chosen victim role - not at all at eye level with other participants in traffic. There is no need for it - if car drivers watch out for others I don't need high viz, if they don't high wiz doesn't help.
In general I cycle for transport and I do this in my everyday clothes that I would wear anyway. Everything else would be silly and too much of a hassle - it would stop me from cycling in many if not most occasions. And looking at myself as a possible victim each and every day certainly would.
Lights: I do run very good dynamo lights (Son/Edelux) on most of my bikes. I do definitively not run flash lights, have never done and never will. As they blind and annoy myself and even more any other participants in traffic. Plus it is proven science, that it is close to impossible to calculate the true distance to a flashlight for other participants in traffic while it is an easy job with a constant light. So while flashlights seem to protect you in reality they do the opposite. I do not run my lights during the day. I do use lights that are German StVZo-approved (which mainly means they don't blind). I do not use battery lights as dynamo lights are maintenance free and just work - I never have to think about them, they are always properly alligned, they always work. Better ones do cost considerable money but reward you with very decent light, way beyond formally brighter battery lights and w/o annoying others.
Helmet: I don't use a helmet. I know that helmets are massive conflict point in most cycling forums and wearing or not wearing one is in the end a very personal decision. Science says that people wearing helmets suffer a lot more from close passes (and those passes are closer, too) and - at the same time - cause more accidents themselves percentagewise and as part of an accident at higher rates percentagewise than people not wearing a helmet. That may be counterintuitive, still it is true. It seems that helmets send out a wrong signal of protection to both, the rider wearing the helmet as well as other participants in traffic. I don't reference the level of protection of helmets in the real case of a crash because this aspect is very opinionated from both sides and no one has managed to come to a clear rational point or unique conclusion - it obviously depends. I hate the discomfort of helmets, the sweating and having to carry the thing around with me. However - I am no fanatic here, everyone to his one taste and belief. Possibly the Hövding airbag may be a good compromise for some if they are willing to pay the steep price. It has gotten surprisingly popular here in Germany.
I do btw. own a helmet and use it when mountain biking. And it is the same with other pieces of special equipment like padded shorts or cycling gloves: I may use it when doing cycling as a sport, but this only happens rarely. Most of the time I do use cycling as a mode of transport or recreational and there is no need for special dress up, let alone putting on a knights armor. I use my bike like I would hop on the bus or enter a car: In normal clothing, w/o special equipment, w/o any mental preparation and w/o any conscious sportiness in mind. That's definitively on thing I really value regarding cycling. It is just natural. And I behave like an ordinary person as well on my bike. I guess that's what is the case in most countries on the continent, most of all in the Netherlands (where basically no one is wearing a helmet, too, despite the high rate of cyclists).
Whenever I've been to the UK in the last years I was really amazed about the differences in cycling: High viz, flash lights, helmets and cameras all over the place. Especially in London a frightening style of riding full of closest passes and gap jumping from both, cyclists and motorists - often pretty aggressive as it seemed to me. And many of the riders seemed to be on a mission - fast, conflict-driving and sporty (vs. the relaxed and natural, but still fast, style I am used to). Get my right: It is clearly not paradise here and there is a lot of conflict with motorists in traffic. Just that cyclists seem to use their bikes with a different attitude than in the uk and see themselves more on eye level with the motorists, as ordinary and equal participants in traffic, less as an endangered species.
Possibly this is part what causes the differences in attitude and equipment and vice versa. As I said in the beginning: interesting.