If a gambling company sent sales representatives to Gambling Anonymous meetings to offer free bets to recovering addicts, there would rightly be a public outcry and that company would likely be penalised or stripped of their license. I can open an incognito tab right now, visit an online support forum for gambling addiction and almost immediately start seeing advertising for gambling; thanks to ad tracking algorithms, those advertisements will start following me around the internet. That behaviour isn't any less antisocial simply because it's automated and online.
The idea that gambling companies should be allowed to specifically target gambling addicts is not a popular policy position, but it's the default behaviour of online advertising platforms. Personalisation and targeting algorithms are innately amoral; they only reflect the values of a company or a society if they are specifically engineered to do so.
This isn't a binary argument between "the internet should be a lawless free-for-all" or "the internet should be regulated until it resembles network television". It is primarily an argument about corporate social responsibility - companies should not be insulated against the externalities of their business practices. We're never going to completely agree on how social media companies should behave and moderating content at scale is immensely challenging, but that doesn't give them a free pass to ignore the risks and negative effects of their platform.