Because of the nature of Moore's law, anything that an extremely clever graphics programmer can do at one point can be replicated by a merely competent programmer some number of years later. ↗
Of course, it's hard to support full-time programmers, so we do get funds from a set of companies that are interested in the health of the Mozilla project and so are willing to support the people working for the Foundation as well. ↗
God, our genes, our environment, or some stupid programmer keying in code at an ancient terminal - there's no way free will can ever exist if we as individuals are the result of some external cause. ↗