A person who collects things can be called a collector. If the collecting is thought to be excessive, such a person might also be called a packrat, or a hoarder.
A person who buys a lot of things is often described as a shopaholic.
An optimist.
stupid, loser
A person who ignores important things could be described as apathetic, negligent, or careless.
A person who thinks nasty things could be described as pessimistic, cynical, or having a negative mindset.
collecter
A person who collects beetles is a coleopterist.
Bibliophile
A cravatologist.
a strawber.
supernatural
A car collector?
a button collector
A paper collector
A badge collector.
A gem collector
Archivist, antiquarian