Hell, I wear a $15 watch from the PX with a velcro strap that's falling apart.
As for the other, the high speed gear issue will depend, a lot of times, on your unit, the budget, connections, mission specs and so forth.
Combat Arms or highly motivated supply NCOs are more likely to either receive or make the effort to equip their people with the high speed gear. The SF Scout weapon light was making the rounds with some of the new units rolling into Anaconda - my unit never saw that kind of high speed gear, but then we also weren't tasked with anything that could even vaguely construed as combat duty. Well, guard towers, but no weapon light is ever going to you a bit of good on Anaconda guard towers, even if someone was stupid enough to get close enough because of all the Apaches.
By comparison, a motor support company I inspected had boxes and boxes of all sorts of flashlights - because their job demanded it. Inspecting vehicles for damage requires clear visibility in dark, hard to illuminate areas.
The L-bend light is a piece of crap - look at it the wrong way and the bulb shatters. I upgraded mine with a Maglite LED dropin for giggles and ended up giving it away.
So why buy a flashlight? Because you never know when you might need one. And just because the Army (in my case) didn't issue me one didn't mean I wasn't going to buy one (or several) to meet my needs while I had ample access to stores in the States. As you might imagine, flashlight options in a deployed PX are rather limited.
When did I use my lights? On guard tower, I used a non-white light for reading maps, inspecting gear and so on. At night, when I had to get ready for duty or hit the latrine, I used a personal light to rummage around without waking up my roommate or tentmates. Working in an office and having to fish gear out of dark corners or when the power went out. Scorpion/spider check - check your boots, check your bed/bag/cot, check the latrine you're about to grace and so on. Walking in an area with no lights but lots of garbage, debris, twisted metal and so forth. A personal favorite - sorting through 150-odd rucksacks and duffel bags that just got pulled off a truck and dumped in a pile. At night and between t-walls with no light.
And those are the casual uses - imagine trying to respond to a hooch on fire or someone down or a mortar hit. In the dark. Without a light.
As for why we elect to spend our hard-earned money on expensive gear: some of it is fanboydom, like the two hundred dollar watches. Some of it is the Geardo/Fobbit complex - "Hey, the Navy SEALs use this stuff - it must be good." Some of it is talking to an NCO who tells you about the time a Humvee ran over his Surefire and the damn thing worked just fine.
I will never spend $100+ on a pair of Nikes to make a fashion statement. I will, however, spend $100+ on a pair of running shoes to keep my knees and shins intact.
If I had to do it over again, knowing what I know now:
Arc AAA
Bolt AA
Surefire 6PL
Gerber Infinity in red
And maybe, maybe, the SF L5 as the "oh hell" light with a pressure-pad adapter.
Disclaimer: just because someone is a Soldier and a vet is not a guarantee they've given any thought to their gear beyond "oooh, cool" or "it works - great, I'll use it till it breaks and I need a new one".
-Medina
Edit: the subject of knives is an equally long commentary that I'll spare you at the moment. As is the subject of body armor and firearms. A fair number of people, I suspect, wish they could buy their own weaponry.