The software to make these calls is cheap. The calls are cheap. They can make thousands of calls for little investment. So if they manage to do a successful scam in say 1 in 1000 calls they are making a profit. The only thing that will stop them is for people to stop falling for it. When it is no longer profitable they'll go back to whatever low life illegal thing they did before. Sadly, there are too many people who still hand over money to these thieves. So the rest of us have to deal with the annoyance of these calls.