Banking help

I have 4 gold bars in the bank at low investment risk but, over the course of many investment cycles, have made 0% on all of the cycles. I'm adding gold bars as I come across them to the bank but I seem to only hit the 0%. Is that a glitch or am I doing something wrong? Or is my rng that bad? I understand you can do high risk and make a lot but I'm not a gambler at all. Is there a way to exploit this somehow? Any help would be appreciated.