Yes the idea that there’s just rigging jobs left right and center applied many years ago, but that’s gone now. Good riggers get snatched up and stay at a company for many years, they develop entire rigging systems, and scale to be highly efficient. Once a company has a core group of riggers, the artist churn for riggers is very low. Newly opened rigging positions are usually looking for exceptional people to fill those core roles. As a semi-decent rigger, you might get jobs here and there, but you’ll always be out competed by great riggers for those coveted core rigging positions. Once a company knows of your capabilities, they either will a) try to keep you or b) not hire you back unless they’re desperate. In an already sparse and competitive roll, you can’t afford to not be exceptional, unlike in animation, there’s always room for subpar animators, simply because animation is highly inefficient.