alt Hacker NewsKeep following through the logic... You manage to hook someone who absolutely knows you're a scammer, and they keep responding to you taking up precious time you could be spending with someone who is actually likely to give you money. So, what is the upside to getting a response from someone who is never ever going to give you anything?
Occam's razor says they are just bad at English grammar because it isn't their native language/dialect and their education probably wasn't that great.
This is easily demonstrable by conversing with the scammers and noting that their actual English ability is the same as exists in the initial letter. Even when they have no chance of the scam succeeding and have been outed they write the same way. You can see plenty of evidence here:
* https://www.419eater.com/html/letters.php