Among other things, there's malware in the wild that rewrites public addresses when you paste them into the major exchange's "send coins" forms.

https://www.investopedia.com/news/new-bitcoin-malware-change...

Take ETH and ETC for example, they both have the same address format and accidentally sending from one chain to another results into your crypto being locked away forever.

You could ask this guy: https://etherscan.io/address/0xa8f889a066519ffb552a571d553b8...

Looks like he copy-pasted a corrupt version of the address. There are three transactions to this destination, from different exchanges.

I've had an instance where the withdrawal to my wallet seemingly didn't even make it to a block on the chain. This happened on Coinbase and took over 2 weeks to resolve. With their non-existent support I pretty much considered that money lost until the whole thing finally got resolved. But I can definitely see somebody fat fingering the wallet address being one of the bigger reasons.

Well, you’ve also got to keep track of the private key...