While they may not have a big budget, they have 70+ firms producing money in the country, it is estimated that these firms in total are worth around $20 billion or more. Most notable being DHA, apart from road construction and even fertilizer firms, mainly headed by active personnel.
The Pakistan Army also takes a chunk from Government pensions budget. I still remember, my father was a doctor at a government hospital and was sent for Hajj along with a delegation that included some Army ranks including a captain, somewhere along the talk, the captain told him that he will receive 2 plots in a defense phase, and a separate bungalow after retirement.
My Qari Sahab teaches children of Army ranks (majors i believe), in our talk (when I expressed desire to join PAF) he has told me about how big and well protected their villa's are, they have cars, and when they leave, there is one army vehicle in front and back.
I have seen it myself too.
While the lower tier doesn't get much at all, the upper ranks are well off. And that is something you cannot deny. There is an imbalance of wealth.
This doesn't mean they're taking 80% budget, but it does show how much they make via Army firms.
Just because you show a picture of a line soldier doesn't mean upper ranks are under the same condition.