This may have been asked and answered, but I couldn't find it in the forum.

Checking the list of hacked brain wallets (18k) it appears that many used existing wallet addresses as passphrase. A few examples below.

137XrofaWZhaZW2uB7eDsPjcwCNMTXVLot
1BBBvd9G5YThYVVMSGSxJzQvQiQm3WxJC2
16era4SgYEcbZD1pu6oCBXGXjK2wSrePe8
14nuZCWe76kWigUKAjFxyJLFHQyLTsKXYk
1Pjg628vjMLBvADrPHsthtzKiryM2y46DG
1KzSULbG3fRVjWrpVNLpoB6J62xYL42AdN
3BTxuixRkhMQfTSqCLmq9Wn4jJ9H3dszhX
1LdkWzq9DxopPkY1hCmQ3DezenP5PQLNC3
3BHsbqZnUGM5Gbwsxe7ukk8NJc81kfhY8Y
1Q81rAHbNebKiNH7HD9Mh2xtH6jgzbAxoF

Obviously these are easy to guess. I am curious as to why these were used as passphrases. Was there a wallet app that did this, or why did people believe this was a good idea?

Thanks.