What's the faith of zeroconf Merchants ?

[Accardo]

Regading the new Bitcoin core version 24 update that implements full RBF as a way to eliminate zeroconf transactions.
What would happen to the merchants that depends on zero confirmation to thrive their businesses?

From the GitHub PR by Suhas Dafter I am not clear to why some people are opposing this new update. And some stand to it.
If full RBF eliminates zero confirmation merchants from the market isn't it unfair to those merchants who regardless of the risks still utilize zeroconf because of it's fast nature?

If you don't want your transactions to be subject to
these rules, just continue whatever you're doing and don't use nVersion=3."

In the quote above that seem to solve the debate, how will a person who is using the V3 run a transaction with a person using V1 or V2?

Can someone make me understand about this long debate it's not clear to me and which of them are more vulnerable to double spending? Petertodd called the PR  a politics on his comment after making this strong point on RBF

First of all, people do on occasion send non-opt-in-signalling transactions
that need to be fee-bumped to get mined in a reasonable amount of time.
Similarly, it's perfectly valid to try to cancel a transaction sent in error,
regardless of opt-in status. That alone is more than enough reason to support
full-rbf. The need to signal opt-in status is also of course a privacy harm.
Again, that's enough reason to support full-rbf

.

https://github.com/bitcoin/bitcoin/pull/26438#issuecomment-1303164829

[1714276106]

1714276106

[NeuroticFish]

Regading the new Bitcoin core version 24 update that implements full RBF as a way to eliminate zeroconf transactions. What would happen to the merchants that depends on zero confirmation to thrive their businesses?

zeroconf is still optional for now and default is off. Afaik it's version 25 that will probably make full RBF 100% live.
The merchants will have to adapt their logic. They probably were expecting until now too that a small % of users may try to cheat even without the RBF flag on. Now the things get clearer (and easier too for the cheaters). So all the merchants will need to wait for at least one confirmation. Those relying on zero confirmation may have had an unfair advantage over the rest. Now, everybody who wants fast transactions, ... the only proper choice is LN (and this may be seen as political).

[BlackHatCoiner]

There has already been discussion about Full RBF, 0-conf and Core v24.0 here: https://bitcointalk.org/index.php?topic=5403730.msg61346038#msg61346038

Can someone make me understand about this long debate it's not clear to me and which of them are more vulnerable to double spending?

Here's the TL;DR: Most nodes will not relay a transaction that double-spends an RBF-disabled one by default. However, it's a false sense of security to consider 0-conf settled, because miners follow profit (not local rules according to each ethics). It's entirely possible to have an RBF-disabled double-spend confirmed, even if the majority rejects it the moment it receives it.

The other reason is that it prevents potential attacks in Lightning and Coinjoining. For more info, begin reading the OP of the thread I linked above.

[jackg]

They'll likely just change how their system works to handle deposits. If zeroconf goes, they could use lightning for small deposits (I think zeroconf deposits are normally limited to what the service can allow both by User and by the whole service). There's a chance some services might come out too to offer similar systems to banking but for crypto payments (like faucetbox/faucethub but much broader - this could already be a thing and I've just missed it).

Last time it was brought up by a gambling site, they said you'd need 3-5% of hash power minimum to succeed in an attack (you'd probably need more if there was a fee restriction though so it gets mined in the next block).

[o_e_l_e_o]

You appear to mixing things up a bit here.

Here are the relevant documents for version 3 transactions:
https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2022-September/020937.html
https://github.com/bitcoin/bitcoin/pull/25038

This is a separate issue to full RBF.

Full RBF is not being implemented as "a way to eliminate zeroconf transactions", as you put it. It is being implemented to fix various possible attacks, such as pinning attacks, against multi-party funded transaction such as Lightning channels and coinjoins. As a side effect it will make zero confirmation transactions entirely unsafe, but these have never really been safe to begin with.

Can someone make me understand about this long debate it's not clear to me and which of them are more vulnerable to double spending?

Once full RBF becomes widespread, then every transaction will be able to be easily double spent before it is confirmed.

[stompix]

Regading the new Bitcoin core version 24 update that implements full RBF as a way to eliminate zeroconf transactions. What would happen to the merchants that depends on zero confirmation to thrive their businesses?

They switch to LN, simple as that.
The only reason to accept zero confirmation transactions is to not let your customer wait for minutes or even hours after he has paid for his coffee, pizza, and groceries, holding him hostage till the tx is confirmed. Besides, in most cases, if we exclude tourist hot spots the ones paying with bitcoin are just a few, merchants would know them already as regulars, so what are you going to do, scam a grocery store of $50 and then never show your face again there? Not even mentioning the fact that the business can file a complaint for fraud?

It all comes down to a simple thing, will you lose more in revenue from customers, or are losses from theft higher than the profit, merchants always have to balance the pro and cons of everything in their business, and some will get scared after one-two thefts and drop it, some who have just regulars will keep doing so even with this change. Online merchants probably won't even care, they will definitely have the time to stop the shipping, and gambling and exchange sites will just all use the same cooldown some do right now where you're not allowed to instantly withdraw the sum you have deposited despite them accepting zero confirmation deposits and allowing you to gamble with them.