China and India, which are currently the first and second largest countries, have grown to become world economic powers. In my opinion, population is an economic power because business opportunities certainly require a long process from production to consumption, countries that have large populations are certainly a very useful resource and important for the economy.
With the large population of these two countries, the economic chain will continue to run because everyone definitely needs the food they buy every day, so that food and clothing makers will continue to run more stably. Because each of them also has to work in order to earn money for their own needs, so the large number of people living in these two countries will certainly make the country's economic turnover continue to increase quite well. And it will also be easier for anyone to take advantage of jobs that can make more money.
The two countries were indeed well populated, but reducing the number of children being born is not the perfect solution to an economic development strategies, we need to plan ahead towards what we have and create enough capacity that cam accommodate everyone into participating in one or two economical activities that will lead to their sustainability, a good example is China, they are well populated and still yet one of the developed countries in the world.
What you've said is right, but in reality this isn't possible beyond certain limit. For that purpose limiting the population is the only choice. Right now India have got the highest number of young population, but the government isn't good enough to support or provide opportunities. When this is the reality better choice is to limit the population. China had been doing it for a long, the young population have got reduced and now it can't give the support to every person and for this reason they've come with different population control plans which is really good and India will soon follow it.