3ds is shit compared to wiiu, yet people bought 3ds 10x more, people like to buy nintedo handhelds, and switch is a modern nintedo handheld, what did you expect?
3DS being shit is your opinion. 3DS actually has a lot of quality games right now. However it had a very bad first few months until the price drop + quality games came. Switch right now is still very expensive and at launch the games were very lacklustre (for me it's still very bad) but somehow it still sold exceptionally well. It has to be the console/handheld hybrid concept because it offers nothing special content-wise compared to Wii U/3DS launch.