I have a hard time understanding free and open-source software when my future employment will depend on charging for software. I heard a good explanation by someone...everyone but software developers like the idea of free software...and everyone except musicians like the idea of free or really cheap music...if we all just went free, lol.
Most free software is not really free. iTunes, for an example, does not have a separate price, but it is included in the cost of products you purchase from Apple. Both the iPod and iStore generate revenue & profit using the software they provide you for 'free'.
Open source is often assumed to be free. In fact most providers of open source software make money, they just charge for their products in a different way. The basic software, as an example, may be provided for 'free'. They probably also provide a full version which has typical software fees associated with it. They also make money from services that go along with their product. So the software may be free, but they charge for support, hosting services, documentation, education, etc.
My point is, don't worry about future employment because of this. Many software developers in the future will be working for companies providing free software.
There is an old saying - "there is no free lunch". In fact, that is not true. There are 2 types of free lunches. Those you have already paid for and those you are yet to pay for. This applies to software as well.