"Of course, decentralization confers benefits as well, but in choosing the decentralized architecture, you've got to weigh the costs."
It's tough to compare these, because while you can quantify the technical efficiency costs (power usage, hardware costs, etc.) you cannot quantify the benefits. That's because the benefits are almost entirely confined to "removing the need for trust / trustless system". In theory, a system with fully ethical actors would see minimal gain from the increase in trust. A wild west, snake-oil kind of system would see huge benefits.
How do you quantify the greed of mankind?
Great points, these.
There's an ebb and flow between how Facebook grew up and became big and then became ubiquitous - and did certain things with the implied levels of trust along the way.
Most everyone getting involved didn't fully realize that "it's free and always will be" ended up meaning that, to borrow someone's adage, if you aren't buying the product, they're profiting off your data.
This is a great discussion...
Yes, but necessary, IMO.
There is a theoretical framework for this called the "Price of Anarchy"; it was introduced by some theoretical computer scientists about 20 years ago and it's attracted quite a following among the engineer/computery game theorists out there. Essentially, it tries to measure just that - how do you measure the harm of greed?
For the past couple years I've been studying the price of anarchy in some network routing systems, and I agree with you that it's a hard problem - but I think it's an interesting and important one nonetheless.