Considering the staggering size of WalMart (gross sales will hit half a trillion if trends continue), they actually don't post insane profits. Something like 13-16 Billion/year on sales of ~400+.
That said, I think they are actually somewhat predatory in their activities. I remember Sam Walton's style of WalMart. Smaller. Happier workers. Vertical mobility. Lots of 'Made in America' pride.
In rural Texas (and I imagine this is true in many areas), their ability to completely dominate small town economies is staggering. It's bad enough when they apply brute-force pricing that cuts the throats of local small businesses, but it's even worse when they are able to completely flatten a town, and then leave it a vacant husk. This isn't as uncommon as you might think.
Proponents of minimum wage staying low, and of corps like WalMart successfully annihilating attempts to unionize seem to view things through a particular prism. At the end of the day, we still pay the bills. It's just that at the status quo, much of the $ that gets these people by comes from the federal gov't through social programs. You could look at it that instead of WalMart Corp paying the full costs of a typical worker, they pay a portion, then we all (all of us with a net positive federal tax burden that is) pay the rest for them, whether or not we actually buy anything from WalMart.
I like to look at things pragmatically. I actually believe that WalMart might even see higher profits with a few tweaks that made things better for workers. I also observe that their scientifically applied store designs are just a horrifying environment to the sensibility. It's all by design, with tens of thousands of manhours in ordered intensity. The cavernous, industrial-looking interior design, the cheap and annoying lighting, the lack of sound dampening, the completely random layout from one store to the next (so you never know exactly where something is in a walmart the town over), the small signs to make you search longer for things you want, the tall vertical stacks of crap or advertising signage to further obscure clear visual cues on which section you would like to find, the propensity for aisles themselves to be cluttered with crap blocking your path to slow you down, the eye-level stocking of higher-profit SKUs, the end-cap stocking of SKUs with high attachment rates (ie; buy this, but you will probably want X, and possibly Y and Z to go with it), so on and so forth. It's an absolute science. It's as impressive as it is physically and psychically assaultive to experience. The things that one would think would hurt WalMart, such as the horrendous lighting, noise, and clutter, actually cause people to stay longer and buy more on average, due to a bizarre but proven psychological response to stress.
Contrast with a place like Target, where typically the lighting is more natural/easy on the eyes, sound is much more controlled, layouts much more sensible, and general visibility far improved. Of course even a place like Target is still an exercise primarily in profit-making, and so it should be in a capitalist economy, but I do believe they find a better balance, and the prices aren't even too far off in most cases, and in many are just as cheap.
