The size of the packages being sent now is only a fraction of what it was last year. The reality is that the MIC in US is simply unable to produce artillery shells anywhere close to the rate they're being used at. This is primarily an artillery war of attrition and the west is not able to keep up.

When they were getting the Ukrainian offensive going, US had to pull shells from Israel and South Korea already. This was supposed to be the big breakthrough for Ukraine, and NATO threw everything they had into it. Now that the offensive fizzled, there's really nothing else to be done.

The money they are making comes from lend lease and similar, they're planning on gutting Ukraine and installing harsh austerity measures to pay for it all once the war is over. But once the amount Ukraine owes is more than the west thinks they can actually make back, they'll stop supporting them. It becomes a bad investment.