The price just keeps dropping. My investment went from 1,5 bitcoins to 0,34 bitcoins worth of Franko's...

Buy more and your cost average goes down, simple math really. If you buy at the peak of a price you are bound to take a loss, smart "investors" buy all the way down to cost/average their coins.
You buy 10K at 0.004
You need to buy 40K at 0.001 cost average becomes 0.0016. If you are trying to increase your wealth at 25% gain your sell price is now lower to attain such a gain. If you sell all 50K at 0.002 you make 25%.
Edit:
But if you
only spent 1.5
BTC then you probably attained ~375 FRK at 0.004 therefore you
only need to spend 0.45
BTC (750 FRK @ 0.0006) to get to a cost average of 0.00173333.
I am curious if you worry about the people that buy the expensive coins from you when you decide to profit from others, or if your only worry is if you lose in an investment.
Right now I'm worried that I made a mistake believing in this coin. And yes I did buy another 100 Franko's at a price range of 0.0008.
This is a coin with a low supply , which it's a good thing. But the price it's having right now it's not really on pair with the total supply.
Look for example at Unobtanium.
Unobtanium $ 452,783 $ 2.68 169,010 UNO $ 3,787 -6.15 %
Franko $ 49,527 $ 0.35 140,728 FRK $ 815 -3.39 %