Open source vs. Proprietary systems

I think that the pros of open source is as below;
1. Many user community
2. Can enhance the functionality rapidly from anonymous and many users
3. Cheaper to use
4. Easy to modify because the source code is open

Disadvantage
1. May be some weakness in security?

I think that the pros of proprietary systems as below;
1. The souce code is sysmetically maintained and enhanced by a sw vendor.
2. May be stronger in security than open source code(??)

Disadvantage
1. Costly to use and build user community