For every mistake made in the Ethereum world, all participants get a little richer

Sending a transaction to the wrong address will probably burn the ether sent, rendering it forever inaccessible (unspendable), since most addresses do not have a known private key and therefore no signature can be generated to spend it.

It is assumed that validation of the address happens at the user interface level.

In fact, there are a number of valid reasons for burning ether—for example, as a disincentive to cheating in payment channels and other smart contracts—and since the amount of ether is finite, burning ether effectively distributes the value burned to all ether holders (in proportion to the amount of ether they hold).