Instagram? Zynga? There's a lot big minds chasing small ideas 14 years ago
I think to add to you second point. It isn't that the problems are hard/expensive in themselves; it is that they require lots of change.
"The need to change has to be greater than the luxury of staying the same."
Change is difficult. Change needs to be embraceable.
Change needs to be proposed as well though. Change does need big minds.