I've grown used to destructive criticism. I've got a lot of it since I quit my job 10 months ago to pursue a career as a professional artist.
I usually dismiss it and carry on.
One day, Person A -let's call them that way- was trying to discourage me and asked a question:
"You say photography is your job... Do you work 8 hours a day then?".
They weren't looking for an answer, but to diminish what I was doing. Those are the ways of destructive criticism.
I couldn't dismiss it this time, though.
It was true: I wasn't putting the hours. I was definitely getting out and making images, but starting a photography business requires so much more than that.
From that day on, I've been working 12+ hours a day on my photography, 7 days a week.
Even though some people will try to ridicule what you do, the way you take their words is up to you. Use them to your advantage if you can; discard and forget them if you cannot.