As with all elements of life, there aren’t all pros with anything, and the same is no different from computer simulations. Although there aren’t many concerns with computer simulations, there are a few...One of which is using simulation in order to predict/enhance military training, etc. Now, this wouldn’t necessarily be a problem; however, people are concerned that a war may spread due to increased skill in soldiers, etc. Another issue, that has been heavily considered, is that of AI becoming too powerful/intelligent and deeming humans as unnecessary, thus ending our species. The issue has been looked at by world governments and multi-billion dollar companies are also looking into ways to solve the issue.
Other than those concerns, not many other concerns are justified, which leads you to the fact that computer simulations simply help us do things we otherwise wouldn’t/shouldn’t be able to do in reality. Which benefits society greatly when these simulations help us to develop new technologies that can benefit millions of people. Overall though, there isn’t anything to worry about.