It is unfortunately, likely to get worse. You cannot change what is bad in mankind, but we have to accept where we drive people because of poverty into a corner they will act in the worse possible manner.
The obvious answer is they steal the bikes for money. The bad side is the threatening and harming of others to steal/rob them of their property.
Maiming someone is a serious issue and they cannot take this lightly. Examples have to be made of people who do these things.