It seem to be a pretty European thing, I live in the UK and personally wouldn't wear it. The reasons for this being that is still mainly associated with football (soccer) hooliganism, there isn't so much a problem with hooligans anymore but the subculture still remains, albeit usually people of a younger age. Boys (and some girls) who attend football matches at a weekend who are clad head to toe in SI (and other brands such as Fred Perry, Lacoste) who the media portray as hooligans. Football violence has been on the decline since the 1980s and when the first British fans started travelling around Europe visiting other football grounds one of the biggest flexes (if you will) was purchasing expensive designer clothes from boutiques throughout the continent and then showing those clothes off in England as they were not available there at the time. This has remained to this day and any sort of hooligans / casuals (as they're known here) still pride themselves on dressing impeccably, thus SI is still worn by those who partake in the weekly match-going ritual. As a result of this SI will forever be associated with football violence and in recent times SI has also been somewhat linked to right-wing extremism, football subculture tends to portray a strong political message too, and sad as it may be, when the TV is covering marches from anti-immigration and anti-Muslim groups there is often a number of people wearing SI, these people can often be portrayed in the media as the working class unwashed masses (I don't think any reporters care how expensive SI may be)

Roadmen aren't something I'm particularly familiar with living up North but drug dealers I can understand, that badge across the arm is encorporated into a lot of Facebook profile pictures almost like those who ensure their watches are in every picture.