I really could care less if someone copied my information. I like to share documents and other sources I have. Some people don't like it all but they have to expect it if they put their tree out in the public like that.
However, the people who copy are all too often short changing themselves. The trees are usually not documented or they are poorly documented. You frequently see different info on the same people from different subscribers.
Then you will see the absolute same info on the same people from different subscribers but a person is foolish if they think that means it is correct. Too many people are copying without verifying. You can make up a fictitious family tree and it will be accepted. If you disagree with something someone has on one of your family members, the owners of the websites will tell you that is between you and the other subscribers.
Since I have been on the genealogy board which is about 2-1/2 years I have given this warning constantly. Sometime before Christmas I really saw the evidence. I thought I would put in a name of an uncle of my grandfather to see if I could make contact with others. The reason why this uncle shares his exact name with at least 3 other people in the family.
He was married 3 times because he was widowed twice. The tree I found only had him married twice and one was in Newton, Sussex County, New Jersey. She really must have been something! A farmer from Gonzales County, Texas traveled all the way to New Jersey to marry her in 1891.
Then I look further and found out me, my sister, and my brother-in-law were all dead. No dates of death given but we all died in Newton, Sussex County, New Jersey. The only time my sister and I were ever in New Jersey was back in 1956 when we traveled through it going to and from New York. So we have been dead 52 years.
Then further checking I found family on both my mother's and my father's side were married and died in Newton, Sussex County, New Jersey. Since my ancestry is mostly southern American colonial except for a couple of exceptions and the exceptions came in through southern ports, I was really surprised.
This tree was in Ancestry.Com but if it had been submitted to any of the other websites it would have been accepted. This was a person who had almost 150,000 names in the tree. Apparently he/she was picking up relatives of inlaws and their inlaws etc. Too many people who submit their family tree don't consider a good verifiable family tree as important as seeing how many names they can get in their tree.