The way to look at it are that cheaters are a constant factor of the player base that needs to be kept at an acceptably low level. Ban waves provide a trade off

The way to look at it are that cheaters are a constant factor of the player base that needs to be kept at an acceptably low level. Ban waves provide a trade off between hiding information and having a growing population of cheaters that will be occasionally culled. Most cheaters are buying their cheats, will look for ‘undetectable’ cheats to buy and will often find the most popular cheats. As such ban waves tend to catch up a lot of the cheating playerbase. There’s also not much functional difference between banning as soon as a cheat is detected in the population and banning a few weeks later. Some players will have just started using it and others will have been using it for months unless it was found as soon as it was released. The discouragement comes from losing progress, losing money (potentially having to rebuy an account and find and buy a new cheat) and distrust in the cheat author. The downside to banning already detected cheats immediately is that cheat authors have a nice simple, repeatable test to see if their cheat is still detectable which makes development much more straightforward for them.