So as in title, Is it possible to buy really large BTC amounts? like a million $? What was the largest amount of BTC you bought at once?
i think yes its possible if you have big funds in your wallet. but for save play, i think we can buy in a few amount first, and not directly in big amount of BTC that can makes our bank suspicious with our transaction and they will check it for security purpose.
make several transaction to buy bitcoin to avoid if bad situation is happen and don't forget to buy in less than $1000 or maybe in $500 so bank will not suspicious with this transaction.