> Technically, decentralized system will be
    > always slower than centralized one.

This is not a reasonable response to the parent: bitcoin is significantly slower than other systems of its class. Ethereum is an equivalent system and faster. (Others are much faster still)

There are application where speed matters. For example, to sort things out while all the lawyers are in a room.

Ethereum slowed to a crawl as soon as people started trading kittens on it. And I remember seeing transaction fees in the hundreds of dollars when popular ICOs were happening. Which probably didn't help you if you were stuck on one of the exchanges which simply turned Ethereum processing off in times of high load.

Not inspiring confidence in the statement that it is faster than other systems. Compared to Bitcoin it is off by a constant factor, and constant factors aren't really what we're interested in here.

Storing an economy in a fully replicated global ledger has its limitations, there's no getting around that.

I am not saying that speed doesn't matter; trade-off though is security. If there are lawyers to sort thing out, then you don't need crypto.

>bitcoin is significantly slower than other systems of its class

that class being decentralised proof-of-work, it is no slower than it is more secure than those class-members. (And among class members of equal 'speed' it is most secure)