Is it rational for a a company to risk losing $1mm+ while training his replacement rather than pay him more? Assuming he would have stayed if they offered him m

Is it rational for a a company to risk losing $1mm+ while training his replacement rather than pay him more? Assuming he would have stayed if they offered him more money. And if the same situation repeats itself with his replacements, maybe it's a matter of $1mm every (say) 6 years, which would justify paying $166k more per year (surely enough to keep him on indefinitely).