sellers trying to sell used product for 10-20% off of list price

I don’t get it. Almost any item here can be bought brand new from a dealer with a full warranty for 20% off - virtually any and all high end product. Some can be bought for close to 30% percent off. Sellers trying to sell year old product for 20% off are delusional, perhaps hoping for someone to naively buy it at their price but I doubt it happens. If the product isn’t in the range of 40-50% off of MSRP I'm not sure why anyone would buy it as often the warranty doesn’t transfer. Factor in sellers asking for 5-6% extra for Paypal plus shipping charges and even a 30% percent discount really is more like 15% off of list- a non starter. Am I the only one doing this math  ?  I can buy brand new at 25-30% with no extra charge for using paypal or my credit card and minimal shipping. Asking for a friend lol.