Hard Money Lenders / Using Other Peoples Money

Good evening, 

So I'm trying to get a better grasp at the hard money lender options. I have almost 40k saved up and only way that I know is the conventional route. My realtor believes that I go this route as well even though I briefly explained to her about hard money lenders. I see a lot of investors even on social media talk about acquiring properties without a dime out of their own pockets and I want to follow that route as well! Are there really any disadvantages about using hard money lenders? Should I use a different realtor? 

Looking forward to reading the feedback. Thank you so much!