A good majority of the 100 aren't getting any NASA funding.

By some definition of 'fraction'. They are getting basically nothing.

NASA budget is like 30% SLS/Orion for decades+.

> Prove yourself and the contracts get bigger.

If you hard allocate a huge part of the budget you can only give out so many other contracts for the best bids.

The commercial programs have seen significant expansion in scope and spending as their benefits have become clear. The lunar landing contract to SpaceX is a great example of such.

Astra, Rocket Lab, etc. have to demonstrate capability to move up the ladder.

Yeah but if NASA didn't need to spend 4-5 billion $ a year on SLS/Orion many more other projects would come available.

Again, I doubt it. NASA funding doesn't really work that way. They don't get a big bucket of funds to distribute as they please. SLS was the pet project of a number of powerful Senators, to the point where the joke is it's the "Senate Launch System", and has been specifically appropriated for by Congress.

There are ALWAYS politicians who are happy to give the money to their project. The idea that NASA budget would go down by 5 billion $ without SLS/Orion isn't really credible in my opinion. Some projects would be done, because Senators in space states wouldn't want the budget to just get lost.