As far as I am aware (and all this is second hand knowledge as I stopped taking drugs and moved away from it all about 8 years ago, but am still in contact with a few old friends) the synthetic cannibinoids are all nasty and far worse they what they are trying to replace - cannabis. Far more cases of people losing it / psychosis / blacking it / fitting etc than most of the illegal drugs.

As they are easily available, they tend to be more popular among the young (in some areas) who perhaps know less people on how to get actual cannabis.

Hey kids, don't smoke this plant, which is actually pretty safe* smoke these unknown, brand new chemicals some dodgy chemist has knocked up to bypass some laws.

It is all but directly comparable to prohibition, don't drink these safe regulated spirits, drink this moonshine made in some guys bathtub where the profit is paramount and safety be damned.

Yet another case of illegality causing more harm, more problems and costing more than legalisation ever would.

*but not 100% safe, does cause issues in some etc etc