honestly i don't know why saban selling power rangers to hasbro?

Personally I think the big problem with Hasbro owning it now is the leadership. If Brian Goldner (who was incharge of the acquisition from Bandai and was, iirc, VERY excited about adding it to their stable of IPs) was still around then perhaps things would have still been adapted to the very end. Unfortunately, he passed away and the entire brand was treated like an unwanted stepchild in the aftermath. (as we all know all too well by now)
Therefore, I can honestly see them noticing this and just...ignoring it. Goldner might have tried to has out a deal, but no way Cocks or the rest of the current board would give a damn.

so it was saban's mistake.