Traditional home console gamers were cautious after Wii U bombing
Handheld gamers who had just got a 3DS wait some time to get a Switch
Non Nintendo customers only got one after the very good word-of-mouth the system take a while to get
Long-term Nintendo customers (people who used to buy Nintendo and stopped long ago) comeback because... Honestly no idea, maybe they found the system cool and the concept nice, but don't had confidence to buy a Nintendo again. Years of Switch sucess bring them some confidence