I will have to agree with some of the comments here in the past that the marketing of gulden is poor. This is the most likely reason for the low marketcap.  Good if you investing in the hope the marketing situation changes. The development is more then good enough as PeterPicker has stated while comparing Gulden to other coins with a higher ranking on coinmarketcap.

Can you send this link to Rijk or whoever runs marketing for Gulden?