1. pay workers extra (ie. above the market rate)
2. workers are richer now
3. they use that money to buy the stuff you make
4. ???
5. profit!
Has this actually been studied empirically? If you had to choose between paying your workers $1000 more and pocketing it, surely the latter option is the better one? Sure, they might use some of that money to buy your product, but they're not going to spend all of it, and after your own costs (eg. cost of goods sold), you're going to end up with less than $1000? How is that extracting "maximum value from said labor"?