If you can't see the business case, I can't help you.
But to make it simple, if a store accepts returns and these people are abusing it returning chip after chip until they get a good one, how is that NOT going to drive up pricing?
Who says they are "abusing it"? If you get off your high horse and see that any person doing this is within their rights because of the retailers policy then that's your problem.
The retailer has to send another chip which shipping isn't free.
Since when? I've returned a chip that wasn't what I expected but I didn't get another one sent to me, I got my money back instead. So you can say it cost them the initial shipping and it cost me the shipping as well. At least the shipping companies win out? Oh and the retailers too who get exceptional shipping rates overall because of mass shipping. The only person who really lost out was myself, as I had to pay full shipping rates back.
Of the thousands, or hundreds of thousands of chips this retailer sends out every year, how many do you think are being sent back because of not being good overclockers (or in my case because it didn't unlock to a quad)? Enough to raise their prices?
They have to either return to the manufacturer or re-test the returned chip, which isn't free. They have to possibly resell the returned chip but they can't sell it as new or at a new price, so their profit margin is smaller or eliminated.
Yes and if this happens with one in every 10,000 chips they sell, how much do you think it's costing them or anyone? Enough to drive up prices?
Since you insist "The cost of the actual silicon is generally less than $10" then what pays for all the fab equipment, R&D, programming and research? I guess that's all free too.
Yes amazingly enough these costs are diluted over hundreds of millions of chips. How much do you think a few thousand returns of this nature are costing them? Enough to raise the price of CPU's by more than a cent?
Yeah, I don't get it.

Justify it all you want. The world revolves around profit and if you can't see or accept that you are fooling yourself. There's a reason you want to get more for your money but no, you want even MORE. We get it, you can use whatever reasoning you want to justify your actions.
I can tell you don't get it - you clearly have zero concept of the numbers involved here and have never worked in retail either. The $billions made by chip companies compared to the $thousands "lost" for this doesn't even register with them. At the retail level the cost is still tiny - basically it's only shipping fees which is costing them peanuts anyway.
Some of them might not even repay the delivery cost of sending it back (most here in the UK don't), in which case they almost certainly made a profit on you anyway because whatever they charged you for the initial delivery would have been a lot less than what it cost them. You think it costs Newegg $8 to ship an item to you?