It's also eventually they're going to hit a ceiling and be worthless once they're all mined. It seems like a huge bet, trying to guess when Bitcoin value will hit 0.
There may be huge bubble, but that comment is a complete misunderstanding. Suppose all the gold in the world had been mined. Would all the existing gold become worthless? If you think about it, you'll see that just the opposite will happen. The world supply of gold (or Bitcoin) will become more valuable.
I repeat: I'm not saying that there is no bubble.
An aside: Maybe you're thinking that if no more Bitcoin is being mined, then the market can't grow or that there won't be enough Bitcoin to support more transactions. However, there's a plan for that since the original Bitcoin paper. Bitcoin is finely divisible and the idea is that people will use smaller and smaller units for a certain value.