“APTs” are somewhat of a misnomer they are not usually that advanced but they are always persistent they relentlessly go after soft targets and there are way more of them than people realize, especially in the west due to the age and scale of both organizations and IT systems and the fact that these are much more commonly operated directly or supported by dozens of civilian contractors and sub-contractors which their practices are much harder to manage.

Ironically it would probably be easier to run a secure network in North Korea or Iran than in the US simply because of how those societies and their own military/government-industrial complexes are structured.

Its always a question of resources, encrypting the payload won’t prevent discovery, and if it’s not some super valuable zero day there is no point of doing that.
Spending 1000’s of man hours on zero day research is nice when you have an abundance of resources but utterly useless when you don’t since your entire way in is dependent on something that can be patched out or signature blocked at the perimeter within days if not hours.

However going after people and soft targets is a completely different story it can be easily executed, the signature is low, direct attribution is limited and it can be easily scaled up. You can write processes and procedures that instruct operators exactly what to do which means that in a relatively short timeframe you can have 100’s and 1000’s of mechanical Turks trying to find a way in. This is the equivalent of lock picking a brand new Mercedes in the parking lot vs simply going around and looking for an unlocked car.

The first option requires more skill and arguably is more risky since it exposes your activity for a longer duration, the latter can be performed by anyone and at the end of the day yield more fruitful results if all you want is a few hangbags and some cash from the glove compartment.

And Iran isn’t unique I would wager you that this is the way that western intelligence agencies operate too for the most part, the super top secret NSA stuff you see when leaked is executed against targets that can’t be accessed via other means.

Because even tho the NSA has much more money their resources aren’t unlimited and their talent pool doesn’t consist of zero day rainmen that can cause a core dump just by looking at a computer.

The only major difference would be that organizations like the NSA have developed better tooling for these mechanical Turk style of operations but I can guarantee you they aren’t going to be burning zero-days or running super complex exploits and C&C infrastructure if they don’t need too, those are reserved for high value targeted attacks.

On a national / strategic level it’s also makes a lot of sense.

Building offensive cyber capabilities that are extremely costly and requires exceptional talent is risky, especially for a country like Iran.

It doesn’t have as much resources and more importantly maintaining talent is hard both for the reasons you mentioned but also because western counter intelligence can much more easily take them off the board than the other way around.

If Iran’s entire offensive cyber capability would rely on a handful of project-zero level talents then it could easily be wiped out by the US, UK, Israel and other western powers and not necessarily by brute force, bribing people that are extremely hard and costly to replace is just as effective as a magnetized bomb strapped to their Peugeot by a motorcyclist at a traffic light.

And the more complex and advanced something is the harder it is to rebuild from scratch, on the other hand you can probably eliminate 80% of their current operatives and they’ll rebuild their capabilities back to current strength within a year.

This is the nature of and the leading principle behind asymmetric warfare. Seal Team Six is nice, but it costs millions and takes the better part of a decade to create a single operator, cocked up brainwashed suicide bombers however can be just as effective as long as you can get one of them close enough.