Just look at the exponentially rising number of bitcoin ATMs which are currently deplyed around the world. So your argument somehow shows that the comparisons with the early internet actually makes sense. Because at these early times people argued exactly by assuming that there is no network growth. So in the early 90th most people had the opinion that the internet is useless because there are only a few connected computers. Don't underestimate network effects and exponential growth.

Of course nobody knows at the current point where this is going. But you also cannot make arguments ibn which you are assuming there is no growth. Of course the price could go up or down but it is really hard to imagine that it would go to zero.

I have no statistics about it, but I personally think that most people who are once in possesion of some bitcoins will not sell them all, but will always keep a few of them. So the growth measured in number of users seems to only increase. I would consider a net decrease in the number of users as very unlikely as long as there is not a better technologically advanced replacement for it.

There isn't a lot of reality to the idea that bitcoin is "hard". There is such lack of clear one page explanations to get started that people who don't feel like figuring it out are left in the dark thinking bitcoin is wizardry. It's not, that's why we're all exited about how SIMPLE it is. You have 2 numbers associated with your wallet. You send with one number, you receive with another. You protect those numbers like you would your actual cash filled wallet. That's it. If you can understand the grand system of calling someone on your cell phone, you can grasp Bitcoin.

It's safer to buy Bitcoin on coinbase and use those to make online payments than buying online by submitting your credit card information.