This is part of the price you pay when you purchase the most recent tech at retail prices.
If you are one who has plenty of income and is going to use the product for several years, no big deal. But if you purchase something with the intent of reselling it a few months later, you will always take a massive hit.
I purchased my 12.9 128gb with Smart Keyboard and Apple Pencil on Craigslist for 800 bucks, mint condition.
At launch, this same setup would have cost 1,219 pre tax. I chose not to do that, and saved a ton. If I had, I would have understood that resale would be a fraction of the retail price that I had paid.
It's nothing new. It's always been this way with electronics, new cars, and most things that are purchased at full retail price.