A colleague who left was not satisfied with pay. He is now much better paid in the new company. After he left, a person with a lot less skills came in his place.
Someone told me that person is now paid more than the experienced and skilled colleague who left. It's hard for me to believe that things like this happen, but looks like everything is possible here.
That’s actually pretty normal at a lot of companies. When you do a job for years and get used to annual 3% pay increases, you lose sight of the fact that your market value has often increased during that same time period by a much greater rate than those 3% raises.
This is why changing employers to earn higher pay is “a thing”. Your colleague who left? Maybe HE is now the lower skilled new guy who is making more money than the person HE replaced.