Convenience is a real feature
Exchanges can make buying, selling, record exports, and account recovery easier. That convenience is valuable for some use cases.
The risk is platform dependence. Withdrawals can pause, accounts can be locked, and the reader does not control the private keys.
Self-custody requires process
Self-custody removes some platform risk but adds operational risk. Wrong-network transfers, seed phrase loss, malicious approvals, and compromised devices are common failure modes.
A strong plan uses test transfers, hardware wallets, separate hot wallets, written backups, and approval reviews.