Earlier quoted context omitted.
> Mastodon instances will be down in matter of seconds what, why? The load is hardly that high.
For reference, based on quick Googling, Twitter publishes around 10 000 tweets per second on average.
For reference my work laptop (8 logical cores, so 4+HT? 32GB RAM) can handle 100k rows/second sustained inserts into postgres 14 with some batch jobs I'm working on. You can buffer http requests into batches and easily handle way more than 10k/s on a server while still providing synchronous semantics and reasonable latency to the client (e.g. flush batches every 10-100 ms).
I doubt Mastodon is designed for that kind of scalability, but most techies could probably afford to run Twitter as a hobby if they knew what they're doing and they weren't trying to do all the analytics and advertising stuff to monetize it/just wanted to provide the service.