Let's not forget that CBDCs will be a complete violation of a person's privacy. Governments and banks will be able to control your financial life like never before. With cash, it's harder for them to do so. Coins and paper money enable true privacy. They can also be used when there's lack of electricity or Internet access. Say no to CBDCs and yes to crypto and cash. 
Private money complements public money, and the both solve financial transactional needs in the digital era. And since public money (cash) is issued by the Central bank it's the only state money from the government and promotes high level security as you mentioned. Unlike the private money that's created by private or commercial banks which requires intermediaries for payments, not everyone would want to use digital money. Hence, non is replacing any, the both will only work hand in hand to facilitate easy payment. At least when one runs out of cash they can further spend digital currency.