What ancestry has that hardly anyone else does is original scanned documents. That takes time and money to do. It is the documents that are so invaluable, not the trees. The trees are just names, there is nothing to sell, so I disagree with your friend. Mormons are not the only ones interested in their ancestry history. They were just the first major group to start diligently gathering the info.
PS Nobody is baptising me.

The other place to find a lot of good info is through historical societies based in individual areas. I have received a lot of info from those sources. They charge a fee to copy and mail the documents to you. The Arizona archives will send you a digital copy, for example. Some just send xerox's. Many documents are stored in colleges and their libraries will send info to you. ALL charge for it, some more than others. Google books has a lot of genealogical books on line for free download. Those are good sources, too.

Be careful with using other peoples trees. Many are accurate, but some of them just gather and plop in names from other trees and errors get filtered down. Always do you own check of the names before adding the to your tree.

I really like ancestry.com.