I think Some people who are scammed are those who get carried away by greed.Most time the scammer will price your coin higher than real sincere people and without thinking twice and doing some necessary checks to be sure the person is real sellers fall for them out of greed and anxiety.
You are very quite right about this, the world is full of greed so people end of falling victim to scammers, some might even tell them to bring 1BTC and they will use it and trade for you to make 3BTC in 3 days and people will happily believe such nonsense, I wish people could wake up to the obvious fact that like a friend said "trading is a new school and course on its own, if you want to make it then you need to work for it"