alt Hacker NewsL2 networks achieve scale by... Not being blockchain. And by not offering the double-spend protection guarantees of blockchains.
So this statement is "you can scale blockchain tech by using another tech in its place that doesn't offer the same guarantees".
With the Lightning network, L2 is basically a database between only 2 parties that are required to be online during the transaction. It's not possible to double spend in that situation.
There's the possibility of double spending by committing to the bitcoin blockchain an old version of your "database", but then you would face the penalty of having your entire balance confiscated by the other party.
More details here: https://bitcoin.stackexchange.com/questions/67141/how-is-a-d...