Right now his group is THE number one target for law enforcement. Can't imagine something like that not hurting business. If you're a target and you're on the radar 24/7, everyone you do business with automatically becomes a target as well.

The underworld in the Netherlands has always been an unstable place. In for instance the UK and Ireland many of the underworld bosses are able to go "legit" or at least continue to operate from behind bars. In the Netherlands a disproportionate amount of the underworld bosses either get killed or get locked behind bars and lose basically everything.
The organizations in Brabant and Limburg, which mostly concern tight knit families from the traveller areas, seem to have the most longevity. The big city organizations in Amsterdam and Rotterdam on the other hand? Whether it's Moroccans, Surinamese/Antilleans or "old school" Dutch criminals from the city...they usually have a few years on top before they start killing each other or selling each other out.
People tend to focus on the "Mocro Maffia" these days, but when it were just Amsterdam- and Rotterdam-born Dutch guys that ran the show entirely there were also a TON of underworld killings going on. You just heard about it less. There's a reason they called Johnny and Sammy "Spik and Span"; hose two whacked, mutilated and dismembered more people than the entire "Mocro Maffia" combined.