Simple, They just want to get an easy way of earning money. Cheating and stealing are part of our human nature. We do have a devil inside of us and we are fond of taking advantage to those people who we know are vulnerable. Scamming has been around in any type of industry, and we can't contaminate those people as they can easily jump from industry to another. Some people tend to scam due to influence of other people, urgency and etc.
Yes, He/she is correct. Many people scam because they want to earn money easily without doing any hard things to do. Because they do many types of scamming cause they taking advantage of what they know about scam so they use it to get more money in bitcoin.