Wallets aren't part of Bitcoin - they're an implementation abstraction. The blockchain gives you unspent transaction outputs and a way to verify them and sign a

Wallets aren't part of Bitcoin - they're an implementation abstraction. The blockchain gives you unspent transaction outputs and a way to verify them and sign a script to unlock them. The key management involved in a Bitcoin wallet faces the same problems and complications as any other implementation of crypto and user key management faces. Some have implemented it well, some have implemented it poorly.