Sapna no matter how crazy she is or looks, but is a woman of substance...I think she is just wasting her time on likes of Sana who is like a typical low iq girl who cannot read between the lines or understand the delicacies and nonverbal meanings , so there is no use.
Worst of all, she also has Aashka with her again to brain wash her 24 by 7 and transfer her utter negativity in her at every available opportunity.
Even Karishma understood what Sapna really wanted to tell (and sapna was saying all that for the girls' own good & self-esteem) but sighhh, a gullible Sana was crying like a mad child accompanied by Aashka madam to further poison her mind, totally misunderstood what Sapna meant, & Aashka kept added fuel to the fire twisting the things and bending Sana's mind as per her own agenda.
So I guess Sapna is just wasting her intelligence and sincere concerns on people with low Iq and low caliber.
(Ps: I can sense why Vishal overnight jumped onto Sana... the reason is the eviction episode where Salman Khan clearly stated to Vishal that "we were expecting some love angle or something between you two as we thought u r good old friends" from here Vishal took the hint to use Sana to play his game to suatain on the show as long as possible using the tried & tested love angle formula on her as mentioned by Salman).