In the case of CSGO, playing means earning lootboxes, and the items contained therein can be resold / auctioned off. It's the same problem as in Diablo 3 when it first launched, you could sell items found (randomly) in-game for real money. I read one guy's project, I'm sure it was posted on HN, who had 25 bots / copies of the game running to monitor the in-game currency market for deals, then resell those for real money.
Every once in a while there would be a ban wave - implying bot detection and handling was a manual / batch job process - but he'd just get 25 new copies / accounts, the income he made was more than enough to make up for it.
Of course, that assumes he was able to funnel the money out quick enough. And also, both Valve and Blizzard have their own incentive to not be too hard on bots, as they get a cut for every transaction. As long as people don't stop playing / paying because of bots.