Is there any validity to the BTC scarcity argument?

I genuinely don’t understand how one can claim that BTC is truly scarce. Sure, there won’t ever be more than 21 million.

I accept that idea that one can’t simply reimplement BTC separately under another name. No one will want the copycat.

But what exactly prevents others from creating another cryptocurrency that basically mimics BTC, but with a small improvement? If you’re slightly late to the new, improved one, you might be left holding the BTC bag. To my knowledge, there are already distinct cryptos that take the BTC idea and improve on it (faster trading times, lower fees, etc.).

Whereas if you take precious metals, to take one example, gold is truly unique. Silver is truly unique. And barring nuclear fusion/fission, the supply is finite and fixed.

The same idea also applies to real estate. There is never going to be more land on this earth, and nothing could really be created to mimic or replace real estate.

So I don’t really get the BTC scarcity argument. Am I missing something?