Think of it like a musician.
People pirate music all the time "bah who cares it isn't hurting them", and in reality normally it wouldn't hurt them as much (but its one factor why concert tickets are expensive these days). But take into consideration that now most countries are in lockdown, and many musicians are getting $0 incoming and having to revert to other revenue streams.
Yet if people always bought their music, they'd still be getting small amonuts of money in even at the moment as long as people are buying/streaming their music.
Nulled sites not only deprive good, honest, hard working programmers of money, but they also put you AND your users at risk of backends.
If you then feed and support that pipeline by trying to be nice and letting them use your intellectual property, it only hurts you.
Another thing (and this is a personal one), but lets say you started selling PAID addons, and I found you were either currently (or previously) shared your addons with nulled sites, I'd have a hard time trusting your addons or code.
In short by participating on nulled sites, you are ruining your own reputation as well.
Just for a FYI, just one of my paid addons that is listed there has been downloaded 55 times, taking $2700 out of my pocket. They is just one of 15 of my paid addons.
Don't DMCA takedowns work even on claimed DMCA ignored hosts? You can actually pay like $200 USD a year and they'll offer a full takedown service for you.
I despise theft in all facets.