I’d be pretty embarrassed if I was JPMorgan and I hadn’t profited at least ten times that much from illicit private messaging.
And that's just revenue. If the profit margin on your deals was 20% (pretty whopping for banking services) you'd need to bring in 10bn in revenue. That would mean doing maybe $1tn worth of deals.
It's a large organization, sure, but at this point one has to ask just how much they "wouldn't encourage it" or how much do they actually institutionally discourage it.