Trumpism , narcissism, attention seekers.
The need to feel powerful or better then others. Why? Well that depends on each person for the why.
Could be low self esteem;
Narcissism
A Sociopath
A psychopath
A bitter person wanting others to suffer along with them.
An dumb teen/adult having fun ruining other people’s time as a joke.
Fuck someone bored could be doing it to pass time.
In short it could be a lot of reasons.