Probably because they're capable of way more than you're using them for. The ones that just do U2F are only $18: https://www.yubico.com/products/yubikey-hardwar

Probably because they're capable of way more than you're using them for. The ones that just do U2F are only $18: https://www.yubico.com/products/yubikey-hardware/ https://www.yubico.com/products/yubikey-hardware/