They don't make 100$ per console - that might be the difference between the factory cost and the price a consumer is expected to pay, but it ignores, as some have already mentioned, the cost of assembly, packaging, shipping (They can't use the postal service.), storage, marketing, paying the people who make the deals with the stores and sets up the contracts, and the price stores are expected to pay per console.
Most likely, the more units a store buys, the less they pay for the individual unit. (Ie, they buy 100.000 units, they pay 250-300$ per unit, but if they only buy 2 units, they pay 400$ per unit.)
Say that it takes an experienced worker 10 minutes to assemble a PS4 - that's, at the most, 6 units per hour - most likely 4-5. Say it's 5 units every hour, and the worker makes 10$ per hour. At 2 dollars per unit, that means that 50 million units sold would equal 100 million dollars in man hours for the assembly, at the very least.