bitcoin doesnt care if its worth 100 USD, 10.000 USD or 100.000.000 USD. at every price bitcoin has (nearly) the same benefits.
Not really. Bitcoin needs large valuations in order to be able to handle larger transactions.
Imagine international shipping companies wanted to use Bitcoin a replacement for letters of credit. How would you pay for a $100 million shipment if the exchange rate was $1 and there are only 21 million bitcoins?
Because of how the network is set up, the fee to send transactions is relatively constant. It doesn't matter when it's a few cents in USD, but once we get to $500 or definitely by $1000 usd/btc, the fee becomes too high to justify using the bitcoin network for small transactions. People are going to think twice about buying coffee with bitcoin when the fee starts creeping upwards of $1.
Of course, at those levels, Bitcoin can more easily handle larger transactions where the fee is still negligent.