Yeah that's in off-hours, where you get 40% off. So that means it's much more expensive when you need to get to the office during office hours. And your office is not next to the station.
Certainly there are times when it is worth it, and for example 's Hertogenbosch - Amsterdam has a train every 10 min. That is hard to beat. But NS is under a lot of pressure and will get more and more expensive and less attractive as a result.
That to me is insanely cheap. Surely fuel would be like 45 EUR, not to mention the cost of parking in Amsterdam?
Maybe it's just because a similar journeys in the UK (Manchester to London) would be about 130 EUR.
(Assuming I've understood correctly - you pay about 6 EUR a month for Flex Dal Voordeel and get a 40% discount right?)