Disappointing behaviour on Mercari

Won an auction for an item that normally goes 10k yen more used. I paid and immediately after the seller requested a cancellation. I politely ask if they could give me an exact reason as to why and their response was that they were unfamiliar with how auctioning works and they couldn't take down the listing (total BS) despite having over 100 reviews and a history of selling many items before.

I politely but firmly told him something along the lines of "these are just the associated risks of auctions and it is none of my problem" and decline the cancellation request. They proceed to try and gaslight me into believing that it is not a price that is favourable to neither of us or that the both of us would be better off if we cancel.

At this point I realise that I'm not going to get my item under any circumstances but decided to confront once more. They finally admit they were looking to sell it for a lot more, citing that as their 2nd cancellation request. I don't really want to give this person any more attention or thought so just decided to cancel.

I was really shocked at the lack of accountability or 'honour' if you will. If it was me I would have sucked it up, shipped the item and learned a lesson to use the normal buy-it-now listing type.

What's your take on this? Any other poor Mercari/Yahoo/other フリマ experiences to share?

edit: Seller relisted the same item.

edit 2: For those of you that don't know, any party can initiate a cancellation request. A cancellation goes through only if the other party accepts. Declining a cancellation request clears it. It seems that you can initiate cancellation requests indefinitely. You can raise the issue to the Mercari help desk but at the end of the day, it is the seller that is in possession of the item and there is nothing "forcing" them to ship it. My money would simply be refunded the same way as in the cancellation. I don't believe this kind of behaviour would warrant an account suspension so the seller walks free… . Kind of sucks that's why I decided to let go if you will.

by CalligrapherAny125