I mean, some game studios consult child psychologists and lawyers to better implement addictive gambling-like mechanics without being liable for that.

For example? They couldn't consult child psychologists for this purpose. It would be an ethics violation of the highest order and would get any license revoked.

Media does impact the consumer....

What kind of media? Evidence?

But violent games that do reach the market and aren’t dead on arrival are mild in that and can only supplement other, more real problems like mental health issues, trauma, neglect, bullying. And in 99.9% cases it’s just an excuse to push them under the carpet. Like, from drawing a line to what makes older demographics cause daily mass shootings. Not videogames, not even guns mostly, but the environment and culture as a whole.

Again, videogames simply do not influence social behavior. It's difficult to find credible non-biased research, but here are a couple of relatively recent articles:

• Tear, Morgan J., and Mark Nielsen. “Failure to Demonstrate That Playing Violent Video Games Diminishes Prosocial Behavior.” PLoS ONE, vol. 8, no. 7, July 2013, pp. 1–7. doi: 10.1371/journal.pone.0068382.
• Goodson, Simon, et al. “Violent Video Games and the P300: No Evidence to Support the Neural Desensitization Hypothesis.” CyberPsychology, Behavior & Social Networking, vol. 24, no. 1, Jan. 2021, pp. 48–55. doi: 10.1089/cyber.2020.0029

What "older demographics"? "Daily mass shootings"? Where do you live?

All that said, environment does seem to impact social behavior. It's likely a much stronger influence than a recreational activity.