Every time that you shoplift, there is always a chance that you will be caught. This chance is higher for new shoplifters, who might make mistakes. But even if you are an experienced shoplifter, and you do everything right, there is always still a chance that you'll be unlucky.
Let's say you're an intermediate shoplifter. You know to check for anti-theft tags, even inside the packaging. You are very good at concealing in camera blind spots. You can tell when you're being trailed by undercover loss prevention. You also happen to be white. If this is the case, then you have very high odds of success. For the purposes of this example, let's say that you have a 99% chance of not being caught on your visit to the store. That's pretty good. But let's say you make 2 visits to this store (or different stores; it doesn't matter) to shoplift. What are your odds of not being caught either time?
They are 99% * 99%, or 98.01%. That's lower, but still pretty good. If you shoplift 3 times, your odds of not being caught any of those times are 99% * 99% * 99%, or 97.0299%. For each individual time you shoplift, your odds are 99% of getting away with it that one time, but your odds of never being caught ever go down the more you shoplift.
In fact, after 69 shoplifting trips, your odds of never being caught on any one of those trips drop below 50% (0.99^69 = 0.49983703). So even if you are a very good shoplifter who does everything right, after only 69 trips, it is more likely than not that you will have been caught at least one time, assuming odds of 99% for every individual trip.
This is a problem if you need to shoplift frequently. For example, if you have to shoplift groceries every week for the rest of your life, it's likely that you will have been caught after only a year and a half (whereas you may have to stay alive for as many as 60 to 70 years). For groceries in particular, I recommend dumpster diving for them instead of shoplifting, as long as dumpster diving is legal where you live, because that has a 0% chance of you getting arrested. You could do this for the rest of your life without getting in trouble for it.
If you can acquire your desired item for free and at no risk, then do so. Otherwise, if you can't afford it, or don't want to pay for it, only then should you consider shoplifting. When you do shoplift, you should do everything within reason to maximize your odds of success. If you can do something that will give you a 99.9% chance of getting away with it instead of just a 99% chance, do it. Those are far better odds. (What exactly these things are is a topic for a different post.) If you have 99.9% odds of success each time, that will mean it will take 693 attempts for it to be more likely than not that you will have been caught at least once. If you don't need to shoplift that frequently, and you have very high odds of success each time you do, then you could potentially go your whole life without being caught. All of these variables should be incorporated into your personal threat model.
Since a few people here seem to have poor reading comprehension, I'm going to say this before anyone accuses me of it in the comments: I'm not trying to defend businesses by encouraging you not to shoplift when you have other options. I'm trying to defend you, because shoplifting is risky. If you can't bring yourself to buy something from a firsthand store because you know it was made with exploited labor or even slave labor, that's fine. I feel the same way. But for your own sake, if you can acquire that item through less risky means, do so. Dumpster diving is one way. Buying it used from another person may be another, if you can afford it. Only turn to shoplifting when you have no other options.