Alright. I've done a fair amount of work in retail strategy and understanding the business model of dollar stores is extremely important to me.
Dollar stores do not exist everywhere - they exist where they can fill a niche and where they can steal market share. I use the presence as a leading indicator of surrounding economic health, and the expansion as an indicator of economic instability. I shit you not: if dollar stores are expanding there presence where you are, your communities 3-5 year prospectus just got a little bleaker.
How does this work, and why is this the case? Dollar stores rely on extracting *every* available dollar from their customers at transaction time; they erode a consumer's ability to plan, and they put a customer in a cycle which increases their dependency on the dollar store. Holy shit! that's a lot of burden to put on a bottle of shampoo that costs a dollar - and that seems nuts at face value!
Let's say you have $10 (plus tax-ish) in your pocket. In a traditional grocery store you're going to have to pick and choose carefully to spend it. More than likely you'll walk away with 2-3 items, possibly some of which would be milk, bread, and some sort of spread (peanut butter, tuna, etc). That loaf of bread will stretch for a few additional meals, and you'll slowly mix and match additional spreads and nutrients - canned soups and veggies, meaning that your money is 100% focused on dietary intake and the give and take forced on someone means planning and reusing to extend each purchase. Compound on that lose change, and while it isn't a lot - a customer has an ability to save a small portion for either additional supplement or for planning a reward
Now let's take that same $10 (pus tax-ish) at the dollar store. You are going to walk away with 10 items. 10 > 3 - so you must have done better! Except, all your items were designed to give you the absolute minimum acceptable amount of product that could possibly be given for a dollar. This means that the product is astronomically high for $ per ounce comparative to the same product in a grocery store. That can of tuna is now a single serving of tuna, the jar of peanut butter is now 6 ounces instead of 16. Food gets smaller, and more shelf stable. Fresh is confined to american cheese singles and quarts of milk...and if it says 'Kraft' instead of generic, there are 6 slices instead of 8 in the packaging. But you've got 10 items! You've collected a veritable feast! You deserve better. So let's trade out that 10th item that you don't really like and get a candy bar instead. Oh and you don't need two packages of tuna, so you can get the trial size bottle of Tresemme instead... So we've gone from 10 items of food, down to 8 while 'rewarding' our self and buying maybe two day's worth of shampoo for 250% markup. The dollar store took every dollar you had - there is nothing residual.
At the dollar store the customer got 10 items that they were ready to consume immediately, and they were packaged for individual consumption - no planning or preparing necessary. Delivery of goods to customer were provided on time at time - you know, how toilet paper and hand sanitizer were shipped and prepared during the early phases of a pandemic - meaning that you are at a daily risk of a supply chain interruption. Goods at a dollar store are given a 'parity' in packaging - you can see exactly how far your dollar will go, but the value comparison is removed. you can't discount a dollar store. Questionable goods are sold alongside brand names in a dollar store with the only indication that there may be a health risk or quality risk that you may ask your self whether you are getting too much value.
So yes. You can go in with $10 and every time you will spend your full $10. You will get less, you will have to come back and repeat the cycle, moving a greater share of money from you to the store over the same period of time. And while you get the value, you will be eliminating the need to stock as much at the grocery store you used to go to - slowly eliminating staff there, who will now have to shop at the dollar store - while they too try to over-stretch their unemployment and similar assistance...
Dollar stores are the 8th plague.