Journalists at PCGamesN reached this conclusion after analyzing Steam users' game libraries using the SteamIDFinder service.
$19 billion is an approximate estimate. As explained by PCGamesN, only 10% of Steam accounts (73 million) are publicly accessible and found in the SteamIDFinder database. The total value of unplayed games on these accounts amounts to $1.9 billion. To illustrate the situation across all of Steam, journalists simply multiplied that figure by ten.
Earlier, based on a survey of 2,000 residents of the US and the UK, the company Ultra calculated that only 44% of PC games in gamers' digital libraries are played regularly. A quarter of purchased PC games are never played by the surveyed gamers.