One concern nobody likes to talk about is that this might not be a problem that is solvable even with more sophisticated intelligence - at least not through a self-contained capability. Arguably, the risk grows as the AI gets better.
At some level you're probably right. I see prompt injection more like phishing than "injection". And in that vein, people fall for phishing every day. Even highly trained people. And, rarely, even highly capable and credentialed security experts.
I think the bigger problem for me is the rice's theorem/halting problem as it pertains to containment and aspects of instrumental convergence.
[0]: https://simonwillison.net/2025/Jun/16/the-lethal-trifecta/