This video is an hour of Guy Kawasaki asking a panel of teenagers if they pay for any online products or services (no), if they ever click ads (only by mistake), and what they'd do if a free service started charging (switch to a free competitor).
Now that I'm older I have a job, disposable income, and responsibilities that take up my time. I also have an appreciation for the work it takes to create anything of quality. So I am happy to give these people money if they satisfy a need I have and they satisfy it well.
As a developer myself, I think it also has to do with the fact that I hope people have the same attitude towards my product and are willing to pay for my product if they find it useful to them.
A similar example is music - I used to pirate 100% of it, but now that I understand that there is a person and a struggle behind each track, I happily purchase songs from iTunes and Amazon just to support the artist and keep them motivated to do more.