That is the inherent flaw with bitcoin. It has no inherent value and most people who buy into it are doing so on the hope that their 20 bucks will turn into 40 bucks.
But what is it you are buying other than hope? You buy it with real dollars and in order to use it, it must be exchanged for real dollars. It is backed by the hopes and dreams of speculators and fools.
It is a fad. It is the pet rock of currency speculation.
It's cute but eventually it is nothing but an oversized piece of gravel.
Bingo. You nailed the crux of the problem.
When someone brags about the "value" of Bitcoin, do they tell you that one Bitcoin is now worth 600 Bitcoins? No, they tell you how many dollars it is worth. Now, I have no illusion about the US dollar. It is fiat currency, that has been in free fall since Nixon took us off the gold standard, and it is now in danger of losing its status as the World's Reserve currency. It is inflated and kept on life support by the Federal Reserve (double oxymoron there) moving decimal points on flat screens. But then again, the Stock Market is a crack pipe mirage as well.