Indeed. Amsterdam has a fast line to Brussels and from there to Paris now (though a lot of the Belgian track is slow especially around/through the cities). But it's mainly been a huge money sink. It cost billions more than expected, the more local semi-highspeed trains (Fyra) that were purchased were dropping parts on the track and had to be banned.
So now the fast track is used once per hour for a TGV (Thalys). Besides that it's used by the same slow trains that used the regular track before, because nobody wants to invest in another fast train since the Fyra disaster.
The fyra train contract was given to a company which didn't have any experience building high speed trains who promised it for cheap over a reasonably priced experienced manufacturer (siemens).
A case of 'goedkoop, duurkoop' (buying too cheap might end up being expensive) imho.
So now the fast track is used once per hour for a TGV (Thalys). Besides that it's used by the same slow trains that used the regular track before, because nobody wants to invest in another fast train since the Fyra disaster.
It's been a huge failure.