The parties are right wing and racist, they also gain votes from people who just want to be heard and think all other parties are too much like the current ones.

The anti-establishment sentiment is so bad that it also rewards whoever shouts the most outrageous things; if you call them out on it, you're obviously part of the establishment.

They are racist, and are being rewarded for racist statements (e.g. Wilders getting a crowd to shout "Fewer Moroccans! Fewer Moroccans!", or Trump's Mexican wall or keeping muslims out of the US).