Can someone explain why the marketcap of Gulden is low compared to other coins
We are focused on actual developments, not false promises and hype, this means much slower growth but it also means that when we do grow (which is happening slowly but surely) it will be permanent and not a short lived bubble.
and why it's not on poloniex which I trade on?
I'm afraid only poloniex can explain that, as a user of poloniex - if you would like us on there - you should make it known to them that you would like them to add us.
The crypto market is very immature. It's 99% about trading, that 99% does not give a rats ass if the coin is more usable then anything else besides bitcoin. It's all about making that quick 5-10% profits.
In a few years this should change when the cracks form in the current financial system and the coins with no usage will be dumped faster then a hot potato and this is where Gulden will shine if it continues on this path.
Gulden also doesn't have major backing from donors, corporate investors, special interest groups etc everything is done by the people aka community.