Transaction security/privacy on Monero

Sven sells a guitar to a stranger, and gives the buyer a Bitcoin address from his long-term savings wallet.

The buyer checks the blockchain, sees the large sum of money that Sven has saved up, and consequently robs him at gunpoint.

If Sven had instead given a Monero address for payment, the buyer would not have been able to view Sven's wealth.

...

From 'Mastering Monero' book