Re: Profitability
The shop staff in my local store in Bristol were pretty knowledgeable, but given the massive range of stuff they sold, there's a limit how in depth anyone's knowledge could be.
Of course, the big reason I didn't go in there much was the prices, but they did have one advantage which was speed. If I needed (eg) a SATA cable on a Saturday morning, I could pay a couple of quid to get one from Amazon, but it would take until Monday. Or I could walk five minutes down the road and spend about £8, but be home and plugging in my harddrive five minutes later.