50 years ago during the Cold War the economic trajectory of the two wasn’t so different, and pakistan also included what would become Bangladesh. Nixon was opening relations with China after the sino Soviet split, and India probably wouldn’t agree to ally with someone who was in the process of economically integrating with a country that they were actively fighting a border war with (sino Indian border war 1962-present). Pre Iranian revolution Iran was also a major ally and shares a significant land border with Pakistan, and probably most importantly, Pakistan was an ideal country to serve as a funnel for military assistance to the mujahideen to help fight the Soviet Union in Afghanistan, which would arguably lead to the economic drain and political quagmire that was a primary factor in its collapse.
Of course the mujahideen would then evolve to become Al Qaeda which Pakistan would harbor, Iran would have its revolution, Bangladesh would gain independence, and the Pakistani military dictatorship would squander the potential of their country on a nuclear program and trying to maintain an army of equal strength to a country 10x their population. But the choice had a lot more geopolitical merit way back then, and once it had been made it is not so easy as forgive and forget or to counter the logistical inertia just because the circumstances change.
The sad part is that I would hesitate to even call it a social program either - it’s the bare fucking minimum. It’s just taking the money that you paid into it and paying it back out to you later in life. It provides some financial structure and stability to those who otherwise would not have it, and that’s important, sure. But considering that this is height of our vital government social programs, then the bar is already so pathetically low. This is fighting to keep the scraps when private industry is already milking us for healthcare, education, public transit, utilities, etc, etc, etc, and it’s pitiful that we have to fight to even keep this.