I think the amount of accessible bitcoin is far less than 16 million. I would go as far as to say the amount is probably half of that. You cannot imagine how many coins have been lost over the years.
It would be great if you can present some data instead of some inaccurate guess. There's a post up there that you can use to filter transaction data, so you can research on your own. Without something like that, your argument that only half of the supply is left can be easily rebuked by saying something along the line of "you cannot imagine how many coins are not lost over the years even if people believe they are".