alt Hacker NewsLightning isn't even a good solution for most diehard bitcoin users. It's a failed project.
It would take 27 years to onboard every internet user to the lightning network unless you start adding level 3 aggregators and then at that point you lose all the benefit of it being on chain at all.
It would take almost 2 years just to onboard every American assuming during that time there were zero other bitcoin transactions. Then you need to add the fees for the on and off ramps to the individual transaction fees to get the real cost per transaction noting that these would go up quite a bit as the competition between lightning and non-lightning uses of the transaction space would drive prices higher.
The throughput is arbitrarialy limited by bitcoin's current block size, which hasn't been increased since satoshi's era.
Most cryptocurrencies have an adaptive block-size mechanism which allows the blocks to grow to a reasonable size which could facilitate such an onboarding of users. So it isn't a technical problem, it is just a question of bitcoin's current leadership, which is controlled by companies like blockstream.