Bioengineering is inherently dangerous with a high likelihood of disrupting Earth's ecosystems, killing millions of people, etc. if you do something wrong. A key safety step, as they discuss in one of the movies, is making their organisms unable to reproduce so they can't increase their populations unchecked. Which they failed to do. In real life there are people creating new viruses and there is no amount of security that makes that kind of work completely safe.

The book is better than the movie, and Jurassic Park is one of my favourite movies.

Books always seem to be better than the movie, however, movies can be fun. Books give you more information and lets you hear what people are thinking.