A person who does things for others may be an assistant or a helper.
you call it chemist i think
Gemologists
call someone
an industry
Taxonomy.
A critic
a troublemaker?
Someone that doesnt do things for others
Hypocritical
An altruist
This would be an eavesdropper.
Chauvinistic!
Arch
customer
Chemist
some call it collectibles, others may call it ' hoarding"
a trapper hobble