Who was hell made for?

Answer 1

The concept of hell, like many others (virgin birth, resurrection,...) was "borrowed" by early Christianity from other religions. The oldest surviving versions of the New Testament (4th century AD) actually use words from Greek mythology (Hades, Tartaros) to refer to hell. Only much later was hell associated with the devil as Christianity shifted the responsibility for the creation and existence of evil from God to man & Satan.

However:

I form the light, and create darkness: I make peace, and create evil: I the LORD do all these things. - Isaiah 45:7 King James Version

formans lucem et creans tenebras faciens pacem et creans malum ego Dominus faciens omnia haec - Isaiah 45:7 Early Latin Version

Answer 2

Hell was made when Satan rebelled against God.