Seriously, people always downplay how much money a couple million dollars is. Let's say she just spent $5000 on clothes in this chapter. That's 5000/3000000, which is 0.0016. That means that buying an entire clothing store only cost her 0.2% if her new wealth. If she spent $5000 a day, every day for the rest to her life, she would run out of money in 500 fucking years! Half a millennium, spending $5k a day, an never running out of money on 3 million. Thats why its so absurd for one person to be worth half a trillion $$. Shits absurd and people don't fully grasp it
Your math is in severe error somewhere. Spending $5000 a day, $3 million would last 600 days, less than 2 years. Spending $500/day would last 16 years.
Ignoring both interest and inflation, if you spent $3 million over 60 years, that gives a budget of $137/day. $4100/month, $50,000/year. Not bad, but hardly frivolously rich.
Now, $300 million would be another matter. You could spend $5000/day for 164 years.
But she has 300 million yen, not dollars.