First, one is not credible who gets holier-than-thou about "consumerism" while supporting a governmental policy of spending (and printing) money as "stimulus." I'd be willing to split the hair about "spending for the sake of prosperity" (however grossly misguided that notion is) in contrast to spending for the sake of mindless acquisition, but it's duplicitous to castigate people for spending when you really do want them to spend and "stimulate" the economy, and have even in the past given them money to spend. It is likewise duplicitous to wag your finger at shoppers when you support laws creating easy credit or protecting reckless creditors.
Second, it is not as if these people are buying products which are not available at other times, before and after, the sale. Black Friday shoppers are buying the same products everyone else buys, they simply want to pay less than the items used to cost but are willing to pay more than they will cost in the future. (They are also willing to wait in longer-than-usual lines.) Apparently making that particular judgment makes you a consumerist, but buying the same things and paying either more earlier or less later, does not.
Third, no one makes memes when lines for Apple products go around corners and down allies, perhaps because Apple markets to trendier folk who consider themselves savvy clients of the upper bourgeoisie and not icky proletarian "consumers." Apple's lines might be longer and more ebullient if more people could afford their products.
Fourth, the meme presumes people are actually grateful on Thanksgiving, a presupposition. If people aren't actually grateful then there isn't any inconsistency. This seems plausible and if so, then an ingratitude meme would be more appropriate, although less self-satisfying.
Fifth, people like events. People like them because they give purpose to a humdrum routine dominated by work, sleep, and chores. This is just a supposition, but I think some people line up because it is fun, or at least purposeful and out of the ordinary. They haven't calculated prices, places, and times, but get up and go because it's exciting, and it is exciting precisely because they don't know if they'll get what they want. In an age of abundance this uncertainty is rare and, perhaps surprisingly, sought and relished.
Sixth, spending is fun. One feels a sense of agency when one spends, that he can make things happen. So, sanctioned by the apparent scale and inertia of the occasion, some people go an spend regardless of what they need or can afford. Prudent, no. Not shocking either, though.
Lastly, the stampedes and scuffles. These ballyhooed hullabaloos, inflated by crisis-mongering reporting on the nightly news and tabloid presses, seem upon closer inspection to be more rare and less earth-shattering than the stories would indicate. Too, people queue and push and shove for all sorts of reasons, very frequently although in smaller numbers. Have you ever seen people react to the announcement of free food?
So fine, though. Those few hundred people across the nation are dumb. Shame on them. Wicked 'Mericans. Very clever of us to point that out.
The modern world with its abundance and prosperity has a few potential pitfalls, I think we can agree. Mostly we need to respond by cultivating deliberately virtues which used to be adopted out of necessity. We ought not relish scarcity, i.e. suffering, nor ought we grow high-and-mighty in pointing out a minority who behave foolishly on certain occasions and then extrapolating from that event some spurious truism from which we judges are, naturally, exempted.