So the problem with declaring or using Bitcoin as a currency is that it Is not good for the economy of that country if they have a currency which very limited
Bitcoin can be subdivided down to a single satoshi on the base layer, and down to a milli-satoshi (that's 11 decimal places) on Lightning. Yes, it has a finite supply, but it can be subdivided to any value required for day-to-day spending.
the problem is that there is a rich person out there who is holding a really great % of bitcoin
As opposed to fiat, where 8 individuals hold more money than 50% of the human race?
a person who has 10$ worth bitcoin will become 1$ and you and me both agree that is bad for both country and people residing in it.
Again, how is this different to fiat? The value of all fiat currencies steadily declines over time. Sometimes faster, sometimes slower, but always on a steady trajectory towards the bottom.
but now the price has dropped so your whole monthly planning is messed up, your expenses are same as before but your salary is not same, now do you think is a great idea to adopt is as a currency.
So he asks to get paid in fiat-pegged amount of bitcoin. If the price goes up, he gets less bitcoin but the same amount of fiat. If the prices goes down, he gets more bitcoin but the same amount of fiat. If we reach the point where he can pay his bills and expenses in a flat rate of bitcoin regardless of the fiat price, then this no longer becomes necessary.
See there are many economical problems to use Bitcoin as a currency.
None of your arguments assume bitcoin is working as a currency, though. All of your arguments assume that fiat is the currency, everyone uses fiat, all prices are denominated in fiat, and people are swapping back and forth to bitcoin. If bitcoin is working as a currency, then I can get paid in bitcoin and I can spend that bitcoin without ever touching fiat or looking at the fiat-bitcoin exchange rate.