An entire household having iPhones (or even all Apple) is pretty common though particularly if one values features such as Continuity, iMessage and Find My. There's no program but going all iPhones is a choice much like choosing to buy iOS over Android, or choosing the $699+ 11 over the $999+ 11 Pro (or vice versa).
While people may be able to afford to spend $4K on iPhones, why spend an extra $1K much when $3K will do? You can buy 1-3 iPads or Apple Watches with the money saved going the non-Pro iPhone route. Or maybe save the money towards a fancy vacation for when it's safe to travel again.
Apple products are not cheap but if Apple wants to keep a certain level of mass adoption, going $1K minimum on all iPhones is not the way to go about it. That's why Apple releases products such as the 6.1" iPhone XR and 11. I expect their accountants and marketing people have researched and analyzed that the $600-800 price range is where they can get max demand while keeping high profits.
MacRumors forum members are not the norm. Despite these poll results, I expect the 6.1" 12 Max will sell just fine in the mass market. Likely more in terms of units compared to the 6.1" 12 Pro but probably lower in terms of revenue owing to the cheaper price.
You yourself have mentioned not being willing to pay over $900 for a Pro 5.4. Why not? It's just another $100.
I've gottten a few iPhones with top storage so with that and 10-11% sales tax, I've already hit $900+ per iPhone a few times. Based on current rumors though, there's nothing in the Pro models that interest me so between ~$750-850 for the rumored 128GB 5.4" iPhone 12 or ~$1300 for a theoretical 256GB 5.4" iPhone 12 Pro, I'd rather save the $450-550.