There is nothing wrong in keeping money in the banknotes or in your storage at home whatever you call that. Its better to ensure every single centavos you have may it be in crypto, in card or in virtual wallet for as long as you took care of its safely so that whatever may happen, computer may shut down or electric problem you still have something to use on incase of emergency rather than putting it all into one bank and when problem arise you wouldn't withdraw it easily.