To use software as an example, it's much easier to improve upon someone else's work when their work is open source. You fork it and improve it -- much easier than building it from scratch. This process also aids in learning how to write good software, by becoming familiar with other people's techniques.

On the other hand, if you're afraid that using someone else's work can result in a huge fine, then you're less likely to do the project at all. If you choose to do it anyway, you'll have a lot more work to do. There is a higher barrier to entry.