I haven't tried it. Just my humble opinion, research is the number one thing you can rely on. You can go to Google Search and key-in the keywords: earn bitcoin without investment. I'm sure hundreds of pages will appear in front of you. You might find yourself too excited in a way that you don't know where to start. Yet, don't worry. Research takes time. Keep reading until you get the right answer that you want.

If you ask me now, I'm thinking of working for someone as their virtual assistant. This way, you can be paid with bitcoins (if your boss owns a wallet). Or, you can join a bitcoin contest, if there's such a thing. Perhaps, the contest organizer will ask the participants to write an essay about bitcoin mining and, the Top 3 best entries will each win 500 BTC.

There are realistic ways to earn bitcoin. All you need to have is patience. Having the patience to read the bitcoin updates is key!   

Or let me paraphrase: Invest what you can afford. A bitcoin investment is a risk. Every investment system is a risk. Therefore; it's up to you how far you're willing to go within your means. Investment won't make you rich tomorrow but it's a sure way to build better and smarter years after tomorrow.  

This mindset is unrealistic. Bitcoin is only a digital currency, not some kind of a voodoo magic that will make you rich. Getting rich means taking a risk to invest in Bitcoin. Then, take time to monitor its performance.