"Because the price will go higher" isn't really an answer. You can either explain it or you just have faith that it will do what you want. People could use that same argument for everything.
The stock market was never meant to be a way to store value but a public tool to finance and own projects that actually produce economic value. Comparing it to the bitcoin market is a false equivalence.
Why do you care so much about predictable supply if the price is anything but predictable? How is such high volatility commodity a good storage of value? It might be a good speculation vehicle, but people looking to store value typically look for something more stable.
It remains to be seen how resistant Bitcoin is if powerful governments really decide to take it down.
Bitcoin and Blockchain is an interesting project but 1 BTC > 50k USD... Yeah, sure...