I mean that’s just the classic realist security paradox, right? The Iranian regime feels, not without reason, like they need to have a lot of military options to keep themselves safe against both internal and external threats. Those options include missile forces, the nuclear program, the ability to close the Strait of Hormuz, and a variety of regional proxies that can act in their interest and keep their regional adversaries from stabilizing and forming a real threat. However, having all those different security apparatuses makes other nations that have to interact with them (either because they’re also in the region, or they rely on the Strait of Hormuz, or they would also die in a nuclear apocalypse) more likely to feel the need to increase their own security apparatus, which in turn increases the threat they can pose to Iran. Meanwhile the fact that all this investment is going into the military means that there are fewer resources available and less inclination to try and solve problems by other means, making it increasingly likely that any conflict is going to be resolved kinetically, which in turn further reinforces the need for all that military investment.