In my early career, I took it personally whenever someone left the company, especially if I'd hired them. I took any exit to mean the culture was on the brink of failure and it was all my fault.

As I grew up and the org around me grew too, I learned to chill out: to be grateful for the work we did together, to listen critically to their feedback, and to recognize what was and was not in my control. Growth begets change, and exit is healthy. 

Very often I would see them again. Not always as colleagues, but as clients or collaborators of another kind.

I'm eth newbie..just learning
(working on @farcaster)

terminally.online

Not to mention a sign of progress. When people can leave for greener pastures because of the work they've done with you, that is an incredibly bullish signal. You want team members to out grow you.