I think you are missing the above point.
You think of bitcoin as something with a value in dollars / euro's / etc. The point that was made is that, íf bitcoin reaches 1 million, it probably means that bitcoin has become an accepted currency, therefor there would not be a need to exchange it anymore, you would use it like you would use cash right now.
If not, I'm sure that it will not reach that high of a value without potential buyers, so you won't have to worry about cashing in, if you would really want to.
Still, bitcoin is not legalized by a lot of countries, what if i have 10 BTC but i cant cash it out or use it even to buy stuff, this is my concern ATM since BTC hasn't become widely accepted, at least in my country here in the UAE i never saw a BTC ATM, and we have only one registered business as an exchange that's it

I only see more and more miners TBH, and sadly not all exchanges found online are trustworthy and wont deal with international clients for some reason such as coinbase
