doing it on your phone only has one person querying it. Scale that to several thousand and it might appear different.
It amazes me that my comment (while admittedly flippant) got voted down.
It really is true that your phone can update a 50M row table about 10K times per second!
That people are incredulous of this is in itself a stunning admission that developers these days don't have the faintest idea what computers can or cannot actually do.
Just run the numbers: 50M rows with a generous 1 KB per row is 50 GB. My iPhone has 1TB of flash storage that has a random access latency of something like 50 microseconds, which equates to 200K IOPS. An ordinary NVMe laptop SSD can now do 2M. Writing even 10K random locations every second is well within mobile device capability, with 50% headroom to "scale". At 1 KB per row, this is just 10 MB/s, which is hilariously low compared to the device peak throughput of easily a few GB/s.
For comparison, that's about 1 gigabit per second in the era of 200 Gbps networking becoming common. That's a small fraction of SSD write throughput of any modern device, mobile or not. Nobody in their right mind would use HDD storage if scaling was in any way a concern.
[1] Indexes add some overhead to this, obviously, but tend to be smaller than the underlying tables.
That's your reason right there, you used rust! It's both performant and secure!