> IT projects that cost billions are incomprehensible to me, outside of frontier work

Getting a large bureaucracy to agree on a question where any answer will disadvantage some members of it is frontier work. No-one has a good general solution. Very few people even have approximate solutions for a few special cases.

> is there no space in the market for a good software consultancy? Or are they just outcompeted for getting the contract?

You can't grow big enough to bid on these big projects and stay good.