The best way for a society to prepare its young people for leadership in government, industry, or other fields is by instilling in them a sense of cooperation, not competition.

To begin with a given issue, Leadership plays one of the most vital roles in development of any country or organization or society. If there is no good leader then it might be possible that country, organization may not develop well as they should. So I completely agree with the idea that best way to develop young minds for leadership in government, industry, or other fields should be achieved by instilling the sense of cooperation.

Firstly, for any nation young people are their most precious asset. Because they are the future of the country and if they do not learn a trait of good leadership then country might not grow well. One of the most important characteristic of good leader is to listen, every subordinate. So this sense of cooperation is very much necessary.
Moreover, leadership is also not in limited up to managing the people of developing you organization only. A good leader is one who stands in same line with their team mates and still has ability to direct them. If a leader himself does not have quality of being cooperative then organization may not grow well. Another thing, young people in society are the future leaders of country so if we instill the quality of being competitive then it might go in wrong direction. May be one would not be able to lead for long time because of his competitive nature within the organization itself.

In addition, nowadays companies and industries are becoming bigger and bigger. In these giant companies, there are many different departments to mange entire firm easily. So for every department there is different heads or leader is appointed like CEO, CFO, MD etc. If these leaders of the company do not cooperate each other then company's growth may not go well.

On a contrary, some have opinion that if these leaders oneself understand nature of competition, then how can their firm or cooperation grow well. But in my opinion, competition should be done with oneself or to achieve new heights not to demolish someone. While developing competitive nature at some level, people became negative, instead of trying to achieve more success, they start pulling the legs of their competitors.

On a concluding note, Leadership required good sense of cooperation and bit of competition within oneself.