Thanos was a fucking stupid character in the MCU. The human population is currently doubling every 61 years with a growth rate of about 1.14%. Assuming similar numbers across the galaxy, he didn’t do anything except cause suffering. He’s a very poorly written villain.
I guess to stay on topic, they would have looked at population growth, and determined that his plan was moronic, and fought him.
The American government is not giving Ukraine bags of money. They are giving them weapons. These weapons were made by American companies. All of the money spent on these weapons was either spent years ago, or remains in the American economy. The only thing that is moving is metal, plastic, explosives, etc. Money is being pumped into the defense industry, which you would think would make conservatives happy.