Because humans are an ongoing cost and no one has figured how to sell non-consumable slowly depreciating goods as one-off purchases and keep paying your employees once you saturate your market.

Option 1: Artificially sell the thing as an ongoing cost.

Option 2: Artificially make the depreciation cycle faster. Get consumers to regularly replace it anyway with upgrades or trend changes.

Option 3: Make ongoing money from the item via a side-channel (tvs are great at this one)

Option 4: Manufacture and sell a huge number of different goods across market segments and weather the slow depreciation cycle (Oxo does this).

Option 5: Sell some consumable good you can get recurring revenue from along side the item (Coffee pods, printer ink)

Option 6: Make up the money on maintenance, repairs, and financing. Become a bank.

Option 7: Make your money in some other sustainable profitable business and drop the product once you've gotten what you can for it.

All of these kinda suck and option 1 is easy to implement.