$4000 on a 72hr BOB? That's ludicrous. Seagrace was right, in a manner. Yours is a list to cross crap OFF of.
There's BOBs and there's GHBs (Get Home Bags) and just plumb craziness.
Your bag should have a defined purpose or purposes, that'll help serve to constrain what goes in it.
My area, the biggest concern is major earthquake. I was right on top of the Northridge earthquake and totally unprepared at the time. Been a 'prepper' ever since.
My bag starts with water and several means to acquire and treat more. That includes a tool for opening handle-less water spigots. Have a 100oz camelback in it.
A couple CLIF bars, A mainstay 3600cal 'lifeboat' ration, some jerky. Food that will keep and needs no prep.
A set of basic clothes and extra socks. Added jacket in winter.
Comms. Various. A UV-5R ham radio programmed with all the FRS / GMRS / MURS freqs and my local repeaters. A tracphone - any cellphone will work with 911, even without an active cell service contract. A hand-crank AM/FM/shortwave/weather radio that includes a light, mini solar charge, and a USB jack and ability to put juice in a USB-connected device.
A small folding wallet-size solar device that charges a pair of AA batts, which will also server to re-charge small electronics.
Small hatchet, big knife, gerber multitool. A folding pull-saw.
A good-sized personal 1st aid kit supplemented with a bunch of aspirin, ibuprofen, antihistamines, caffiene pills, sewing kit, suture kit, butterfly bandages, various bandaids, moleskin, light, pencil, paper, fire, and an additional kit with a bunch of 4x4 gauze, gauze rolls, ace & coban wraps, 'trauma kit' with clotting agent, strap tourniquet, and some dowel rods that will work as a splint.
poncho liner.
a handful of mylar emergency blankets.
local and regional maps.
$200 in cash in small bills. spare keys to everything. A thumbdrive with encrypted scans of my important documents and identification materials.
50rds of .22, 25rds of 9mm
a boonie hat. A lightweight windbreaker.
trash bags, various sizes for various things. Some gallon ziploc bags. Most of the items are also grouped in such to make rooting around in the bag fast.
Some batteries, various.
some duct tape on a collapsed roll.
A roll of TP.
spare eyeglasses.
and yeah, there's a deck of cards in there.
I don't think I spent more than $300 on the whole thing and much of it I had laying about already.
I probably forgot a few things. That's my basic bag for sudden unplanned events. That's the bag I'll have running out of the house, abandoning my vehicle if it isnt' safe to stay with it.
At home (again, I'm in big earthquake country) there's a 55gal drum with removable lid with the wrench for the lid clamp nut duct-taped to the lid. It's away from the house, in a pool equipment enclosure. Inside it is 10gal of water, a set of sturdy clothes and shoes for everyone in the house, a set of heavy tools for tearing back into the house / garage to reach a lot of stored water and foodstuffs. Full sized axe, 10-lb sledge / maul, crowbar, more saws.
We can bail out of the house at a moment's notice with enough stuff to survive the immediate cause, then access the things we need to get back into the house / vehicles to more stores. And we keep enough fuel to top off both trucks, load up and drive far away to scattered family or out of a danger zone. Whatever comprises that danger.
if the danger is other people, we have the arms to defend ourselves. I have a 'possibles' bag to go along with each longarm, which includes items both general and particular to that firearm.
As to general prepping, we follow the 'store what you eat' principle, rather than going nuts on buckets of mylar-wrapped basic foods or very expensive pre-packaged dehydrated goods or stuff like MREs. Had enough of those in the Marines. I do however keep a bunch of basic ingredients in gallon mylar bags. Each bag labeled with contents, packaging date, basic prep instructions. A LOT of canned goods. Costco is Good. Got a nice chest freezer for bulk meats mostly.
George Carlin used to have a funny skit about 'packing a smaller version of your stuff'. The context was a trip to the Hawaiian islands, but the concept applies to prepping. Akin to the 'line gear' modus in military gear arrangement. You essential gear is ON you or near to hand, redundant in many places. Each layer you add more capabilities, more sustainability. Some of it is mobile, some of it is not. You don't try to make one method do everythign and you don't put all your **** into one bag / place / basket.
An earthquake won't get all my stuff. A house fire won't get all my stuff. A mob won't get all my stuff. The govt can't get all my stuff. A divorce won't even get most of my stuff.