Mainly trading or gambling. But if you want a way to earn bitcoins without those risks, you need to do like you earn physical cash: Working.
Sell products for bitcoin, or create your own business.
well besides gambling and trading there are also so many ways to earn bitcoin, also gambling and trading involve so much risk and the lose of money is compulsory in trading and gambling, however the most easy way to earn bitcoin is signature campaign which is very convenient and without risk.
correct! these are the most risky ways to earn more about bitcoin. and i agree with you that just by joining the signature campaigns, we can have huge amount of bitcoin as a rewards. especially in the ICOs signature campaigns. i must say that thru that, i have just earn a good amount.