@Kang_Kong3 @Shlomo Well there's the lure of adventure, combat experience. You might get a FEW guys, but most of the fighter jocks are smart enough to be successful in better careers: After 3 years of grinding war, they understand that any yankee going to fight under the ukrainian flag will be in a constant state of stress and logistical underinvestment.
US warfightin' boys are the prissy princesses of war today. They expect top-tier support treatment, intelligent leadership, and constant resupply. Their training is built around it. They're leery about going up against extremely experienced surviving russian pilots in an F-16 on its last 150 hours of airframe life, with half its instruments covered up with post-its to remind him they're non-functional.
Ragged, broken down aircraft, constantly inoperable parts, feckless leadership ordering you into dangerous situations (and ignoring your expertise) are basically expected there. That's a bad deal if all you get is cool stories and some kill tallies on the resume. Delta Airlines offers a much better deal in every other way but bragging rights!
In contrast, there ARE guys taking contracts to fly in iraq still. Know of one old guy back on the grind down there for half a year. Not a single pilot in ukraine in my extended circle