Hyperloop wasn't an idea for "how to do it better" because Hyperloop cannot do "it" at all. The nameplate capacity of Hyperloop, granting all of Musk's fantasy parameters, is in the low thousands of passengers per day. High speed rail can land a thousand people every minute.
Nit pick: About Japan's busiest high-speed rail line (Tokaido Shinkansen), Wiki says:
At peak times, the line carries up to 16 trains per hour in each direction with 16 cars each (1,323-seat capacity and occasionally additional standing passengers) with a minimum headway of three minutes between trains.
Not exactly "a thousand people every minute", but I agree with the jist of your post. High speed rail has orders of magnitude higher capacity.
Excellent point. Shinjuku station in Tokyo is the busiest train station in the world by passengers, and it does not have high speed rail ("shinkansen").
Isn't there a pretty solid argument to be made that hyperloop (and especially what Boring Company is actually building) is so dumb that it shouldn't seriously be treated as a good faith solution and other motivations should be considered?
I don't agree. The whole Hyperloop thing was not an alternative implementation it was a pitch for a completely different society altogether. Instead of moving everyone in California at a reasonable price, let's have a giant infrastructure that is at least as large and disruptive as rail but only serves a tiny slice of the ultra-rich, everyone else has to take a car.
It wasn't "how to do it better" it was an attempt to reframe the entire question of whether medium-distance mass transportation should exist.
I don’t know where you’re getting this from. The idea has nothing to do with only serving “a tiny slice of the ultra rich”. You’re adding all this dramatic extra stuff about society and reframing.