The main problem is that a lot of Lightning, ecash, etc. wallets allow you to associate an nsec to unlock the wallet. Not many people pasting their nsecs into random vibecoded apps are security-conscious enough to use a separate Nostr key, so if one of those vibecoded apps leaks nsecs, you can pretty much scan the respective lud16 for half a dozen popular wallet domains and, more likely than not, hit the BTC jackpot.