Question about nondeterministic wallet I was reading https://github.com/bitcoinbook/bitcoinbook/blob/develop/ch05.asciidoc#user-stories and ran into this statement.


  In the first bitcoin wallet (now called Bitcoin Core), wallets were
  collections of randomly generated private keys. For example, the
  original Bitcoin Core client pregenerates 100 random private keys when
  first started and generates more keys as needed, using each key only
  once. Such wallets are being replaced with deterministic wallets
  because they are cumbersome to manage, back up, and import. The
  disadvantage of random keys is that if you generate many of them you
  must keep copies of all of them, meaning that the wallet must be
  backed up frequently. Each key must be backed up, or the funds it
  controls are irrevocably lost if the wallet becomes inaccessible. This
  conflicts directly with the principle of avoiding address reuse, by
  using each bitcoin address for only one transaction. Address reuse
  reduces privacy by associating multiple transactions and addresses
  with each other.


In the first part, it says multiple keys are generated and used only once. But in the second part, it says that the address reuse is a problem.

But if each key is used only once, how are they being reused?
That is what Andreas is trying to convey. He is saying that the traditional way of generating random private keys for each transaction in order to prevent address reuse is a poor choice of wallet principle. That is because every time you generate a new random private key, you would have to make sure to keep a backup of it so that you can recover bitcoins tied to that private key in case your wallet software becomes inaccessible. If you are transacting multiple transactions a day, generating a new address every time, you might find it tedious to back up your private key every time. The other way you get around this would be people using the same address so as to prevent the hassle of backing up the keys.