Existing large projects will continue. The problem is creating new ones.
There is no reason new projects cannot be created. If you know of one besides your supposition that wealth must be concentrated in few hands, I'd like to hear it.
Getting together a large number of people to invest large sums in something doesn't work worth squat. Look at the biggest Kickstarter projects--7 figures. If the price of entry is too high it won't happen without concentrated wealth. For an example of something of this sort that's both important and effectively impossible to do with little-guy funding, look at SpaceX.