If dev can't show BTC address with at least 500BTC from shares in it, it's fact he is scammer! I know he is, that's why he won't!
I know in the past he got a page with all transactions of premine.
Some people are out of gulden, the premine is not open more
Gulden + premine = dev got free money? I don't know...
I think gulden have already cleared that they have 170M premined coins which is 10% of total coins so whatever will user mined can stake or dump on exchanger. As well all premined coins are staked can check here
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Gulden already have good market and there is certain audience who use NLG currency at shop.