> this work ONLY if bitfinex has higher price than other exchange

Bitfinex might well have higher BTC/USD. However, the reason is that people can't get USD off Bitfinex, and so buy BTC to get those off Bitfinex. Thus, if you try to do the arb, you buy BTC cheaply on exchange X (for USD), then sell BTC (simultaneously) expensively on Bitfinex (getting USD).

Now, to realise your paper gains, you either have to wait for the BTC price to converge and then unwind the trade backwards, and have some money left, or you have to get the USD off Bitfinex. But you can't. That's why the price of BTC was so high there in the first place.

TL;DR: Arb is not trivial.

If no transfers are necessary, that basically means it stops making money when your long or short position is maxed out. A transfer would be used to allow bigger long and short positions to be entered.

> and even him didnt clearly wrote that this work ONLY if bitfinex has higher price than other exchange...

To be fair, it does not appear to be pointed out in the readme.md, either.

First table, named "Implemented Exchanges".

That table does not make the point raised here, which concerns a specific consequence of Bitfinex being the only exchange you can currently short bitcoin on. I would provide the specific quote, except it is already in the post that you replied to.

>Where is HN from 5 years ago? :(

Here: https://hn.algolia.com/?query=bitcoin%20arbitrage&sort=byPop...

As you can see, there wasn't much discussion. The noise has certainly increased, but at least there is a discussion going on now.

An increase in volume of discussion does not seem to benefit anyone aside from folks who read discussions in lieu of doing anything else.

For that, reddit is ideal.

Was HN ever a place to talk about financial speculation schemes?

If you want to talk about this stuff, you want a forum full of financial trader people, not engineers.

Yes it was. It was much more business oriented than it is now.