As it has been clarified it is not 4% daily but 4% annually which is a huge difference, anyone that claims that can give you 4% daily is trying to lie you and deceive you, no exceptions, but a 4% annually is completely possible, however this is the problem, are you going to be willing to give up having complete control over your coins just for a 4% increase increase on your capital especially when those kind of results can be gotten by making a single bitcoin trade during the year? To me it doesn't sound like an attractive option at all.