One of the reasons that make open source software so attractive is the freedom to modify and share what other people have done. It is the perfect solution to avoid reinventing the wheel. With most paid applications, years of development go into making them good. Many times, the company goes out of business. When they do, thousands of man hours of time and energy are wasted and lost. All of the solutions and problem solving that went into the products are not available for others to build on. This dramatically hinders the evolution of technology.