There are different factions within The Hand.
The Hand is more complicated than we thought. In Daredevil, The Hand is seen as a seedy underground organization with a horde of skilled fighters and the uncanny ability to revive the dead. The second season of the Marvel series revealed that The Hand’s sole motivation was to locate a secret weapon known as Black Sky, a harbinger of evil who we now know is Elektra. But in Iron Fist, we learn that The Hand is also extremely divided. Madame Gao’s synthetic-heroin operation is actually a rogue, drug-pushing faction of the organization.
Meanwhile, the main faction is more of a recruitment operation. The Hand has been recruiting and teaching kung fu to young, disadvantaged teens, who are then stationed throughout the city like a spy network. Basically, The Hand has eyes everywhere, all over the world. Colleen Wing is part of that organization, and her dojo has been feeding The Hand scrappy recruits for years. Though she thought she was part of a peaceful operation, once Colleen becomes privy to her sensei Bakuto’s shady and extremely violent dealings, she begins to question The Hand’s real motivations. It’s only after Bakuto tries to have Colleen’s blood fully drained — a direct tie-in to Daredevil Season 2’s creepy blood-draining facility and those zombie teens — that she renounces The Hand completely.
But what is all of that blood for? A popular theory is that The Hand is draining the blood of young people to feed to Elektra, their now-immortal weapon, who’s currently resting in her stone urn. It might also have something to do with IGH, the nefarious medical operation that gave Will those red and blue pills that drove him crazy in Jessica Jones.