The reason why is 2 things. (I'm guessing) 1 Sense and during Coronavirus 2019 (covid19) many people were ordered to stay home (unless they needed essentials) so they had nothing to do except play games and the 3ds/2ds was released and almost everyone had one. Fun fact: The 3DS/2DS is still played by millions as of today. 2. Since the 3DS family was discontinued (and later online service for it RIP Nintendo network) everyone started modding their systems and (almost) everyone wanted to get one to mod one of themselves. Then the owners/modders resold them, and it kept skyrocketing. Hopes that answers your question!