"proof of work is a waste" - a common argument advanced by numerous people in their first ten posts.
The proof of work IS the leap that makes it all work. Without an understanding of why the proof of work is important, there is absolutely no understanding the fundamentals of bitcoin.
Without proof of work, there is nothing stopping from someone creating thousands of virtual validators that look identical to a thousand real ones, similar to how a computer can look like ten computers through the magic of virtualization. What good is 2/3 of the vote, if I can have as many votes as I want?
Well, if you think about it, it'd just turn into more of the same. You can't have as many votes as you want, but you could have many millions, billions, or trillions of votes. But at some point, you'll max out hardware. And then, you're back to having proof of work, or voting by power level of hardware.
It'd be the same amount of "work" for farms of computers around the world, just executed in a worse, different manner.
FWIW, I still believe Bitcoin isn't quite right. I think block rewards should go on forever, and I have advocated that since very early on. I see a currency that just stops growing causing deflation and hindering economic growth. An ideal currency would have no inflation or deflation, and that only happens if you have a constant minting that will eventually equalize with the amount of coins lost on accident + the growth of the world's population.
But, I still think Bitcoin is a great project, and fully support it. It's still the best that is available.