This is debatable in that you are focusing on those who will pocket the freebie and then do absolutely nothing, a category nobody has ever negated the existence of, and at the same time doesn’t exhaust the complexity of observable behaviors.
I say category but pay heed it’s not like a single actor is attached solidly to any category, people hop from behavior to behavior depending on a variety of factors, so I certainly have grabbed games from mass giveaways for no other reasons that they were free to take, too, but here I am considering <brace yourself> buying games that I very much enjoyed even though I have them on other platforms.
I guess in this case it is fair to say that the degree of enjoyment can be measured by the propensity to spend on the game. In fact, even though my yearly gaming budget, if divulged, would probably be cause for some mild surprise, I have bought multiple copies of games I think are great for no other reason than to spread the love.
Back to topic, truthfully the only people who can tell you whether freebies are a net positive or negative on sales probably do not post on this forum. It’s also very likely something that is very much situational, also because not all freebies are created the same (for instance, the studio behind Thimbleweed Park has no other game for people to buy, just very minor, cheap DLC, and a similar consideration applies to Giant Sparrow, whereas Subnautica devs Unknown Worlds clearly were hoping people would be enticed into getting Below Zero.
As for me, I can only add that when I’ve instilled the doubt that there may depth and facets to a matter that go beyond “I do what I do, so everybody else must be doing the same too”, I guess I’ve done my job for mankind and can go crash my weary bones somewhere comfortable.
