According to the latest study [1] estimating how much money cheat developers make annually it is an upper limit of ~ $75M. I would say that the very liberal estimation of anti cheating efforts will cost maybe $100M annually. That does not include only research efforts but actual cost of tackle them (extra compute, reviewers...etc). This is unrealistic but even through to reach the point of billions (2-3 billions) you would say that Gaming companies were spending on average $100M since the beginning of personal computers era (on research only). This is not something that is hard to believe even with the most liberal interpretation.

So I think it is fair to say the there haven't been billions of dollars of research spent on this problem.

[1] https://www.dexerto.com/gaming/anti-cheat-study-reveals-chea...