Well, I don't think everyone is investing for just profit. For me is an insurance if things ever get really bad in the future for our economy. On global crashes people return to gold to keep their money safe. I guess that they will probably return to bitcoin as well when the next crash occurs.
Also bitcoin could really become a reliable currency in the future. If it ever achieves that, it will have to become a global currency, meaning that $16k is just to low. So who cares if it will take 5 years or more. If bitcoin succeeds in it's goals it will be much more valuable than it is now, and it could actually become an option to be used, and not just to be sold for profit. What will a merchant do, when people will start asking to pay with bitcoin and not with anything else?
This is something that I doubt gold will have. People will not start using gold as a currency, but bitcoin will probably take that path and become more valuable and useful than gold.