Yes, you have to invest money, you need to buy hash power in order to mine, I've used Hashflare for over 2 years now and have made thousands of dollars, the best thing to do is invest what you feel comfortable with and turn on reinvest, that's what I did. I currently have 8.44 th/s and was making over 20 dollars a day before the crash, now I'm making a little over 8 dollars a day which I am reinvesting until bitcoin rebounds.