Question: What are the difficulties of a technical or an open source software is the biggest risk is what??

Question: What are the difficulties of a technical or an open source software is the biggest risk is what??
I think the first difficulty is to use, and greater difficulties and risks as He Yunwei, especially online (not intermittent) service (if you use this software);
Why?
Because, like cars, car, all kinds of cars, learn to open the first difficulty, but if the car does not know who the car, then the car breaks down how to do on high speed,
you want to repair themselves, you have to understand the principle of the car;
Similarly, you want good operation and maintenance software, you need to understand how it works (or you have successfully repaired experience);