The last rewrite I've seen completed (which was justified to a point as the previous system had some massive issues) took 3 years and burned down practically an entire org (multiple people left, some were managed out including two leads, the director was ejected after 18ish months) which was healthy-ish and productive before the rewrite. It's still causing operational pain and does not fully cover all edge cases.

I'm seeing another now in $current_job and I'm seeing similar symptoms (though the system being rewritten is far less important) and customers of the old system essentially abandoned to themselves and marketing and sales are scrambling to try to retain them.

Anecdotal experience is not so good. Rewriting a tiny component? Ok. Full on rewrite of a big system? I feel it's a bad idea and the wisdom holds true.