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 collects things is typically called a "collector" or a "collector specialist."
A person who buys a lot of things is often described as a shopaholic.
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.
That person could be described as manipulative or deceitful. They may engage in passive-aggressive behavior to provoke or upset others.
collecter
A person who collects beetles is a coleopterist.
a strawber.
Bibliophile
supernatural
A cravatologist.
A badge collector.
A paper collector
a button collector
A gem collector
A car collector?
Archivist, antiquarian