Gabe Newell is a CEO of a very small company, staff-wise, can’t feign ignorance.
That company runs multiple games with lootboxes and doesn’t make any attempt at restricting gambling from underage customers. They were restricted from doing so in some jurisdictions, can’t feign ignorance.
If you go even deeper there is evidence of Valve being perfectly aware (and amused!) that their item marketplace is used to facilitate offsite gambling on esports events.
Gabe Newell runs multiple online casinos.
Are you one of those people that think Uber is a tech company and not a taxi company because they have an app?