alone in a crowd

This is my worst favourite.

An oxymoron is a figure of speech that is also an opposite in terms, i.e: a lonely crowd. “Alone in a crowd” does not strictly conform to oxymoron list.

I think “alone in a crowd” is a parodox instead of a oxymoron.

lol nice oxymoron

wow yo it amazing

A paradox is a series of statement or theories that contradict themselves, and may create an infinite loop.

This is not a paradox. Owned by teenager.

“Alone in a crowd” is both a paradox and an oxymoron. Paradoxes and oxymora aren’t necessarily mutually exclusive. Also, the definition you provided isn’t the only definition. For example, Merriam-Webster’s definitions:
1
: a tenet contrary to received opinion
2
a : a statement that is seemingly contradictory or opposed to common sense and yet is perhaps true b : a self-contradictory statement that at first seems true c : an argument that apparently derives self-contradictory conclusions by valid deduction from acceptable premises
3
: one (as a person, situation, or action) having seemingly contradictory qualities or phases