Not saying it’s right or worth the disproportionate investment, but the true value is the threat they pose keeps other countries in line (to a degree), winning the battle before it starts.
If you win a conflict decisively, then the conflict is over and weapon sales dry up. Continuous, low-level, indecisive battles are what keep the weapon dealers in business.
I’d argue that the additional funding has allowed the US to leverage the investments they’ve previously paid for in their regular budget to help Ukraine.
You cannot throw the money congress has budgeted for Ukraine at a vacuum to get nearly as much support - you need the logistics of a ready to go military industrial complex that everyone loves to hate.
Aid given to Ukraine has mainly been material the US already has. We aren’t building new weapons for them. The dollars on the aid packages is the value of the equipment.