Thanks for the knowledge shared, then I have no problem using those open-source wallets all I have to do is keep my private keys safe, once again thanks for sharing this knowledge.
As mk4 said, open-source doesn't automatically mean trustworthy and secure. The idea is that an open-source wallet can be reviewed by hundreds or even thousands of programmers around the world. Developers can easily inspect the code and assess its quality. However, they will not be able to examine every piece of source code that is published. The reality is that many open-source programs will never get properly reviewed or tested. And because of all the open-source code out there, it can happen that the code is not 100% clean.
Because of the nature of open-source, and the sheer volume of it, mistakes can sometimes go unnoticed. This would be the case for any open-source project, but for open-source wallets, this issue is much more pronounced and can potentially lead to a huge financial loss.
I am not saying you should be skeptical of a open-source wallet in general. What I am saying, is that when in doubt, go with a well-established open-source wallet (like the official Bitcoin core wallet) or one of the open-source options that have been well-reviewed and heavily tested.