If someone think Bitcoin is gambling I think they don't know what Bitcoin really is. Maybe they only know some risky way to earn money from Bitcoin such as invest in HYIP system, Dice or Bet. Don't waste your time to show them what is the real about Bitcoin cause they will never understand it 
. I've tried a lot of times before but person whom I told them about Bitcoin still think Bitcoin is really bad and risky ))
That's true. As long as bitcoin do nothing bad to us then we don't have to defend or explain anything about bitcoin if they think it is a bad thing such as gambling. I invested only my time here, but i can't say I wasted it because somehow i earned something valuable. But i hope time will come, those people will change their minds toward bitcoin.. I've tried a lot of times before but person whom I told them about Bitcoin still think Bitcoin is really bad and risky ))