Why has the price of the Nintendo 3DS gone up so much?

Six years ago, I bought a 3DS and 6 games for 150,000 KRW on Karrot Market.
Since I don't play games anyway, I was looking for something to sell,
and after checking the current Karrot market prices, I listed the 3DS and 4 games for 450,000 KRW, and they sold instantly.
Why on earth has the price risen this much? I thought the retro trend had passed,
but it's even more expensive than the Switch OLED.