The point is that "amateur" means literally "lover" in latin. While "professional" means "for money" today, in latin it meant "to profess a vow to do it with high standards".

For example, you can be a professional, but do things "pro bono" (for free or for public good) or "pro lucro" (for money).

"Doing something was a high standard" is still the main meaning of the word "professionell" in German. So someone can make something "unprofessionell" for money or "professionell" without payment.

Another word of classical origin with a striking difference is the meaning of the word "pathetisch" in German, which means "(exaggeratedly) passionate", which corresponds more or less to the meaning of the Ancient Greek word "pathetikos".

"Vocation" has undergone a similar shift; originally it meant a calling, or a summons.

It still does.

Just don't go looking for the etymology of "vanilla"

> The point is that "amateur" means literally "lover" in latin.

It doesn't mean anything in Latin. It means "lover" in French. Possibly a version of French from before "love" changed to "aimer".