Close to us: The world around us is made of atoms and molecules, and reactions are going on inside us, in the environment and in space.
Living things run on chemistry: Biology is interesting for its diversity and relevance to our existence, and what biology can and cannot do is often controlled by chemistry.
The planet (and universe) runs on chemistry: Chemistry is important and complicated on Earth, in the sea, in the atmosphere, in stars and other planets, and in space: environmental chemistry, geochemistry, marine chemistry, atmospheric chemistry, astrochemistry. Cannot understand these things without knowing some chemistry.
Beauty: Pretty colours, glowing things (reactions like combustion → fire, chemiluminescence), explosions, flavours, smells, plus the beauty and symmetry of some chemical structures and the elegance of certain chemical theory (see below).
Technology: Stuff like computers, plastic objects, dyes, paint, washing up liquid, margarine, ice cream, washing powder, antiseptic wipes all need a lot of chemistry knowledge to invent and improve.
Industry: Chemistry can make industrial processes cheaper, more efficient, less damaging to the environment (catalysis). It can invent (or make economically viable) products that would not otherwise exist (polyethylene, silicone, conductive polymers).
Morbid curiosity: Weird things like poisons, explosives, and other dangerous substances, and how they are kept at bay, plus drugs (see below).
Geometry and symmetry: Interesting shapes and structures of molecules and other collections of atoms (such as clusters, crystals, amorphous solids, liquids, polymers)
Patterns: Interesting patterns in structure, bonding and reactivity seen in many substances, some otherwise apparently unrelated
Creativity, skill and artistry: Creative challenge of synthesis
Utility: Chemistry makes useful and interesting products (medicines, building materials, fuels, colours, foods, fragrances, ). It is satisfying to understand how new and useful things can be made, and even better to actually do it yourself
Simplicity and elegance: - systematises many diverse observations, a few simple (ish) concepts lead to massive diversity, can often be unified through mathematical and physical models. Chemistry provides insights into the strange but true behaviour of small things like electrons (quantum mechanics).
Makes you good at other things: Studying chemistry is likely to make you more logical, better at critical evaluation, better at creative and strategic thinking
Unique selling point: Not everyone is interested enough in chemistry or doing well enough at it to study it beyond compulsory courses. If you are, your talents are in demand and you can make a difference to society and nature in a way that not everyone is able to.
have a long history and (I think) have always been part of human life
are an important problem in society: bad for the taker (detrimental to health, illegal hence risk of punishment) and bad for the rest of us (drugs trade is unregulated and leads to other serious crime like murders; health problems caused by drugs cost society money)
effects are sometimes desirable in the short term (euphoria, relaxation, stimulation) interesting e.g. cannabis, LSD (hallucinations), ether
relationship between the chemistry of drugs and their effects is complicated and interesting, and sometimes sheds light on pharmacology or biochemistry in general
interesting for the same reasons as legal substances like alcohol and medicines - because pharmacology and related fields are interesting in their own right
