As a scientist I should support such a project, especially one located in the suburbs of Chicago. But at what cost? As a perspective, next year's proposed budget for the entire National Science Foundation is just over $6 billion.
This ILC reminds me of the Superconducting Super Collider, a project that spent $2 billion dollars digging a hole in Texas that was killed by Congress in 1993 once the projected costs topped $12 billion.
Putting large dollars into a single basket will take away the incentive to increase basic research funding in other scientific endeavors. The main argument for the ILC at Fermilab is not that the research won't get done, it just won't get done in the US. So let the Europeans or the Japanese have the flashy expensive collider and let the US do what it does best—basic research advancing science over a large range of disciplines.