Problem isn't immigration, it's birth control, or the lack of it!
We live in a country where maternity hospitals are practically baby factories, churning out babies day and night relentlessly!
Statistically, the fertility rate of Pakistan is 3.5 babies per woman, which is rather... Extreme, if you ask me! For comparison, U.S has a fertility rate of just 1.6, whereas India stands at 2.7.
I've nothing against babies but... I do have a thing against overpopulation. Economies have limited resources, and each new person puts a little strain on it, which eventually adds up and makes a big impact.
And look at the deplorable condition of our economy. We have pushed our economy so awfully far that we are practically neck deep in debt. Too many mouths to feed, not nearly enough food, metaphorically speaking.
But despite that, the government and the people, no one seems to be interested in controlling the population, which is going to swallow us whole sooner or later. China realized it back in the late 70s, hence they enforced a one child policy. Now sure it created lots of problems for them but I think a two child policy should work just fine.
We are far from the 1 billion mark so we still have time.