$3~4B is indeed quite big budget. However, it's dwarfed by big tech's R&D budget. FB alone spends $20B+ each year.
I guess one key difference is that unlike FB, DARPA money doesn't need to be confined to make quick and visible returns, thus they can focus on more long term problems.
I guess one key difference is that unlike FB, DARPA money doesn't need to be confined to make quick and visible returns, thus they can focus on more long term problems.
[1] https://www.macrotrends.net/stocks/charts/FB/facebook/resear...