[baby]

You are missing the "trust" element of a blockchain. A blockchain essentially allows you to run a distributed database where the different actors don't trust one another. Tradfi is built on trust of entities (can I trust this bank? Can I trust this central bank? Etc.)

[siddthesquid]

Yes, that trust is the fundamental difference. However, that trust costs money in the form of needing more nodes.

You usually can trust your bank, as long as you trust your government. Regulations make it difficult for banks to misbehave.

That being said, not trusting your government (which I can believe is a valid stance in some countries) is probably the only valid use case for blockchain IMO.

[baby]

I would say it cost less money, running a bank is a massive cost, entire cities like London, New York, and HK are built around the banking world.