The 1982 Tycoon Returns from Abroad, Spoiled and Fearsome

[Period Setting + No Romance + Feel-Good Story + Building a Career + Fake Tycoon System] The heroine's personality: hard to describe, and not exactly a good person. She transmigrates into the year 1982 at the age of eighteen. Before she can even celebrate, she runs into human traffickers... The tycoon System that comes with her is a trap: not only does it make her spend her own pocket money, but what it unlocks and duplicates are the businesses she used to own! Thankfully, her grandmother is only sixty this year. She can still laugh with delight and scold people when she's angry. She still has family by her side to listen to her chatter. You took care of me when I was little, so now I'll take care of you in your old age... (The setting is partly fictionalized. I've done some research, but please keep half your brain switched on while reading.)