Let's put that another way: if you're not afraid of being seen as the dark lord of an evil empire in order to get what you want (which, in Gates' case, seems to be "billions of dollars to solve the most important problems the world has to offer") then you should follow in his footsteps.
If you are destroying a part of the world to fix another, you are not good. You may be evil even. Because you are selfishly choosing the part to fix, in expense of the part you destroy. If you are good, you should do no evil, or at least strive to.
In other words, if you have world-changing vision, and want to succeed on a truly massive scale, you probably have to Think Like A Supervillain (http://dirtsimple.org/2009/02/everything-i-needed-to-know-ab..., http://lesswrong.com/lw/gp7/think_like_a_supervillain/).