QGIS is open source software, so it relies on a huge number of individuals and organisations to survive and develop. Some of the people who work on QGIS are paid, and some are not - but the results of their work are available to all of us. Some organisations pay for developments which help them. This model means that (in the words of Paul Ramsey at FOSS4G 2013):
But you don't need to be a developer, or to have money to spend, to contribute to QGIS. You could:
You could do these things a lot or a little, or you can just use the software and swell the user base! But remember there are some dedicated and clever developers working on the project, so if you do nothing else, tweet or email them every now and again to say thanks :-)