Quote from: o_e_l_e_o on March 06, 2019, 10:50:55 PM

I had assumed Bakkt would have to accept zero confirmation transactions anyway? Or do you have to "pre-load" your Bakkt account in advance before actually buying anything? If that's the case, this is a far less interesting development.

Still, I would have imagined Starbucks would be able to accept zero confirmation transactions, provided they had opted out of RBF. The chances of someone going to all the effort of setting up a double spend to save themselves 0.001 bitcoin on a coffee is tiny.

it reads like people will have to pre-load like a gift card but i'm not sure. it's all very vague.

you don't need to double spend (in the mining sense) to screw them over if they accept zero confirmations. you just need to use a simple script to re-spend the same outputs with a higher fee before the first transaction gets confirmed. at considerable volume or at higher values, that's probably a significant risk for any merchant. bitpay seems to have stopped accepting zero confirmation tx some time ago, probably because they got screwed over like this.