Whether or not is useless, the promoted tab is meant and created for promotion and thus you supposed to advertise there . And if it's useless, it's because ignorant people choose to pump hundreds into bots and thus rendering it useless.

How come there are not suppose to give a positive roi ? So users are using it to loose money you say ? It may work in china this type of mentality, but not everywhere . You don't go to work to loose money; such as you don't invest in something to loose money; it's supposed to give you a profit, that's another reason for why people want to use them , and thus again rendering Promoted tab useless . But people like you, ignorant by nature, submit 100 steem in a 3 dollar worth of vote . No wonder it gives negative roi . And don't you have better things to do with your money hence you have this wasteful mentality ? What about making a donation to @minnowsupport - they help minnows grow
or @curie - they curate good content that's out there
or @steemcleaners - the they clean the platform of people abusing the pool rewards, overuse bidbots, make dumb, bad or rubbish content etc .

I am taking responsability of my actions, become self-responsible to bring up to the platform what kind of users we have around us, and hopefully clean them off this platform if they don't straighten up to be a fair player . You see, not everyone is pumping 300 STEEM in bots just bcs they don't care what they do .