I really hope that skinny wire isn't carrying 120 volts....it looks almost thin enough to be telephone or door-bell wire....
Also, it seems to me that that black conductor is 300-ohm twin-lead wire used for TV and FM radio antennas. Please tell me that stuff is NOT connected to the Romex!!!
At least they used the proper tape for splices. Could have been worse -- either paper "masking" tape or duct tape.
When I was house hunting in the 90's, my real estate agent showed me a house that had a couple things like this in the attic. "Don't worry about it!" If a housing inspector comes up here, I'd never get a mortgage because I could never get fire insurance. "Naw, it's OK. They don't look for stuff like this." Thanks, but I'm switching agents. BTW: They had also converted one of the smallest second floor bedrooms into a furnace room for central heat. The attic floor was an obstacle course of flexible ducting.