You're assuming BTC will appreciate in value. There is no guarantee it will eventually become worth millions of US or equivalent dollars.
Even with a fixed qty; uncovered exploits, technological breakthroughs, change in crypto trends (aka a move to another platform), or change in society could halt an increase of value.
Technically the same is true of gold. Even with out a massive change in qty, something as simple as a better gold like alloy for jewelry, an alternative for electronics, or a sudden cultural aversion to gold ownership could reduce the value.
Even with a fixed qty; uncovered exploits, technological breakthroughs, change in crypto trends (aka a move to another platform), or change in society could halt an increase of value.
Technically the same is true of gold. Even with out a massive change in qty, something as simple as a better gold like alloy for jewelry, an alternative for electronics, or a sudden cultural aversion to gold ownership could reduce the value.