Incompetence? Money laundering? Stupidity?

I’m sure by now that most of my few readers have seen the US Air Force superduper, ultra-stealthed, invisible to detection radar, very expensive, cutting edge technology F-35 jet fighters that have been shot down by Iranian heat-seeking missiles.

Can someone explain to me why NO-ONE at all in all those years of development within the engineering department, military, procurement or political circles thought that jet engine exhausts were hot and could be seen by IR scanners when spending $400 billion to design and build a totally stealthed fighter jet?

Did they think that the heat-seeking missiles were old technology and were obsolete and/or no longer in use?

Or did they just not realise exhaust gases are hot?

Group think circle jerk of incompetents, modern educated “experts” and a young Playstation experienced, social media addled generation of engineers who were mostly subcontracted at cheap rates and decision making by braindead military procurement bureaucrats and idiot politicians who believed the hype and who are without critical thinking processes springs to mind yet again.

Were these young engineers also the same type with the same educational standards as those who designed that submarine that imploded a few years ago on a dive to the Titanic that used Playstation controllers to operate it after the company replaced all the older experienced submarine design engineers with these young box ticked for DEI passed engineers?

Or was it all just a big money laundering scam?