I think that there is a lot more money in the world right now than 20 years ago and definitely than 400 years ago.
A lot of it is just dumb (people inheriting money or getting it for other reasons than intelligence or financial acumen: singers, athletes, etc.) and some it is exploratory/inherently risky (VC) or both. So a bubble can last much, much longer and be much, much bigger.
We're probably going to see more of these.
I guess at this point I should probably just say that I regret not being smart/connected enough to be at the collecting end of one of these hype trains :-)))
This seems more likely to me than someone at Facebook saying "We need a our own money system," evaluating blockchain against a centralized design, and deciding for technical reasons that Facebook Money should be a blockchain project.
This is pretty much how it happened. A Bitcoin fan started at Facebook, started from "how do we use a blockchain here" then came up with something to use a blockchain for, and recruited some executives who thought similarly.
Most of what's weird and dumb about Libra/Diem is because it was started by four bitcoiners, from bitcoin ideas. It turns out that ideas from a cryptocurrency that was started in order to evade government control don't play well in the heavily regulated environment of Other People's Money.
The only legitimate reason I can think of would be cynically drafting on the hype cycle. But I've been reading David Gerard's book Libra Shrugged [1] and it looks like the actual answer is that "blockchain" has a quasi-religious belief system built up around it, and the people involved are members of the faith.
One of the stunning things for me about "blockchain" revolutionary hype is how long it has gone on without significant accomplishment. It started only a bit after the iPhone, which has had a huge impact on things, including payments. It's hard now to imagine a world without the internet in one's pocket. But if every blockchain stopped working tomorrow, few would notice. Contrast this with M-Pesa [2], a different approach to digital money. It started at around the same time but has had huge uptake. A recent report in Kenya [3] says M-Pesa has 30 million accounts, which is approximately the number of people in Kenya age 15 or over. To me, that's what successful digital money looks like.
[1] https://www.amazon.com/dp/B08M8DGKY4/ [2] https://en.wikipedia.org/wiki/M-Pesa [3] https://ca.go.ke/wp-content/uploads/2020/07/Sector-Statistic...