> As they say, the best way to ruin something you love doing is by making it your job.

As someone who made a job and career out of what I always loved, it's far from ruined. Your relationship with the thing changes, and like anything that changes, sometimes it will go well and sometimes it will go bad, often both in succession like a rollercoaster.

> IMO people who chase some higher purpose and meaning are destined to be forever unhappy at their job.

I can 100% agree about people like that being forever emotional and passionate at their job. But to label it as unhappy is terribly reductive. "Unhappy" is a part of it, but there are plenty of other emotions you will go through: happy, scared, hopeful, dubious, frustrated, satisfied, elated, etc. Much like emotions that play out for us in "real" life events and relationships.