Part of the tax money will be given to the share holders as dividends. The corporation can reinvest the money collected from tax to conduct government businesses to earn more money for the corporation. Most of the tax money will be used to build our cities. If our cities, our medical technology, or our education improves, our economy also improves. If our economy improves, the corporation can collect more tax.
More tax means more profit for the share holders.
This corporation is just like a regular corporation. Investors will be attracted by the corporation because it is the world's biggest, most reliable, most stable business. This government corporation does not even need to give share holders dividends, and people will still invest in it's stocks. You cannot lose if you invest in this business. The corporation can invest the tax money in various businesses in order to earn more money for the corporation.