Well, the rates on such sites like xbtfreelancer are not very good because the competition is too high. You can make a living with freelancing but you need to find projects in niche sectors like the dark web. There are a lot of projects which giving out work for good rates because there are not many developers available.
It is possible with freelance project that pays you in bitcoin like in xbtfreelancer. I have already tried some projects in there like data entry, mystery shopper, web edits and logo making. Those work pays you in moderate to high value of bitcoin. Thats like the same with earning a living in a real job.