Basically mine are pretty much similiar to most people here.
First is basically getting addicted to "martingaling". Where you think its not possible to get 20+ losses in a row. This is the worst feeling because every sequential bet is a huge loss to your balance and your heart just sinks if it rolls "red".
Second is also pretty common. Sometimes I manually set my bets and base bet sizes, so I do lots of manual clicking on the "Roll" button, however sometimes you move the mouse wrong and accidently hit "MAX BET" and you click Roll and its a loss. Hence why its a good idea never to keep all your BTC at your account.
I think we all have experienced this, that feeling of excitement and at the same time anxiety, knowing that you could win or lose at the same time. There is no assurance but just the mystery until it happens. Its either regret or happiness which you will encounter. I think when your balance is going down, you start to feel scared until you have that winning bet. Its always like that, just gamble occasionally, thats my opinion.