@Oran silvester the story doesnt present mincheol's loan as something he used for a clear legitimate purpose. Mincheol used the loan mainly to cover immediate financial struggles, but due to poor judgment and possibly misuse, it spiraled into massive debt burdening Hae-soo. At some point in the earlier chapters it's insinuated that he took those loans under her name. So he's simply just irresponsible and a jerk