Someone needed to send some bitcoins to another person they had a deal with and so asked for their address. The fellow sent an address and he sent the coins. Almost immediately, they sent a chat and was like "Have you sent it?" He responded in the affirmative and they exclaimed "Oh no." Even though they didn't give me details of the problem, I think it could be a wrong address or an inaccessible one.
In my experience, I haven't had any cases where bitcoins were lost due to an incorrect address (or something similar). This is because I usually double-check the address.
I remembered this incident because sometimes, I do not cross-check addresses when I send small funds. Have you lost some bitcoins because of carelessness?
If you don't check your bitcoin addresses, you'll one day tell us a new story about how you lost a bitcoins (but with details from the original source).

Of course, I've lost a bitcoin by accident, but those were due to "errors" of a different nature, namely, the recipient's dishonesty.
What are you most conscious about before clicking the 'pay' button?
Did the last few digits of the address match correctly with the numbers on the hardware wallet screen?