i disagree. you are completely ignoring second layer solutions
comparing the rbf feature with paypals reversability is also a wide stretch. i wouldn't count transactions in the mempool as final, that is what you basically also say. but no "honest" vendor should accept zero confirmation transactions anyway. or maybe there are some, willing to take the risk
Can you explain the second layer solution?
Even if there’s a second layer solution you’re talking about then how will you fix double spend problem with unconfirmed transactions, which is unfixable because you’ll have to wait for 1 conf.. atleast and that will take a lot of time considering the queue of customers behind you waiting for you to make complete your payment, funny.
sorry, i missed your question. you always have to wait for at least 1 conf, transactions in the mempool don't even count as final in my mind. for example on the lightning network you open a channel with 1 transaction on the base layer, you wait for as many confirmations/blocks you like, after that you can use the channel "infinitely" until one day you settle on the base layer (1 more transaction). so if everything works as expected you touch twice the base layer to do "unlimited" transactions inside the channel. you go to the merchant with an already open and confirmed channel, you don't open a channel when you are standing in line to buy something. hope that is clear. the lightning network is fascinating, you should look into it
(there are other scaling solutions, but i am digging into lightning atm)Aren't second layer solutions mainly meant to solve micro transaction problems? Who is going to try a double spend attack for a couple of dollars? I am not quite sure if I understand all of the second layer solutions, but would someone who is willing to double spend attack a second layer transaction also have to have the majority of the hash power?
see my answer above, there is no problem with double spends
(someone more intelligent than me correct me if i am wrong). and you are right, that second layer solutions are primarly meant to buy a coffee for example, a transaction not everyone running a full node needs to have in its ledger. but that doesn't exclude larger transactions. on the lightning network they removed a limit not long ago, so now there are quit big transactions possible. depends on how you define big, we mostly compare the sats sent to the dollar value, which will go up infinitely in my opinion