This is what I like the most on this doubler , the site name fits to it. Also when you look at the "Rules" tab on the site, you can see the warnings there before investing to the site. Unlike other doublers before that claim they have skilled and professional for-ex traders blah blah blah to double your investment

admin of honestdoubler is too honest, admin is warning investors that they may lose bitcoins when they invest?
Yes they do and actually admin is saying the truth 'cause this kind of game aka ponzi may collapsed anytime when they got few new investors and it will stay as long as there are new investments coming everyday unless admin will run away (worst-case scenario)