Often, when people talk about the reasons why one should build apps for any platform, they invariably mention money. The popular ploy is to tell developers that App Store X is a gold mine just waiting for their special creation, and that they'll be able to quit their day jobs once the money starts rolling in. And while there certainly are examples of app millionaires, and countless others of people who make a decent amount of extra cash from their apps, I've chosen not to highlight money as one of my three reasons.
Why? I believe money isn't the primary reason many people build apps. Sure, few of us would say no to bringing in some dough from our work, but I believe the real reason most of us build apps is that we want to scratch an itch, to pour our creative talents into something, and then share it with as many people as possible. Money is nice, but I believe that reach is just as strong a motivating force. Maybe you have an app idea that improves your work, helps to manage your day, or helps your kids with their schoolwork. Most of the time you'll build that app first to help yourself, and then to help as many people as possible. Sure, you'll want to get paid for your work, but building something that thousands or even millions of eyeballs will see? That's a good feeling.
Reach is an important motivator, and there's no doubt that Windows has reach. The current install base of Windows is somewhere around 400 million PCs. Of course, that number accounts for all versions of Windows, so we're not talking about 400 million Windows 8 users at the moment. Even still, Microsoft did recently report that Windows 8 sold 40 million copies in just the first month of release. That's impressive by itself, but even more impressive when you consider that Windows 7, Microsoft's most popular OS to date, didn't sell near that many copies in its own first month. We might be entering a post-PC era, but with Windows 8, Microsoft is along for the ride. By building your app for Windows 8, you open yourself up to millions of users who can benefit from your ideas and creativity.