1. Sufficient liquidity didn't come into btc/fiat markets.

Exp: For the next decade atleast, till we transition to using Bitcoin to buy goods and services, exchanges are necessary to onboard people. Especially Bitcoin-focused exchanges. More volume on spot markets for different fiat currencies is better. Especially for those outside of USD, EUR, GBP, CNY, JPY and the other big ones.

2. Connections between full nodes aren't sufficiently private.

This is what projects like BIP324 is trying to achieve by raising the cost of doing deep packet inspection, MITM, etc.

3. Supply chains of ASICs doesn't get sufficiently distributed.

We need more manufacturers from the global south producing ASICs outside of existing production regions.

4. User-friendly Privacy.

I don't have well-informed thoughts about this except that developers think existing privacy solutions are not sufficient to make Bitcoin fungible.

Personally, I think taproot made multisigs more private.

5. Lightning UX.

Of course Bitcoin has to scale and existing UX on lightning is simply not good enough. Important question is: can people without technical expertise be able to run a node, open and close channels and route transactions. I believe we can get there. We must get there.