If good money and just not breaking the law are two requirements, then looking into certain niches might not be a bad idea.
Google calls these niches "sensitive" https://support.google.com/adsense/answer/3016445?hl=en.
Here's an example, an online poker statistics SaaS making $2.9M Gross/Yr https://feinternational.com/buy-a-website/50471-saas-recurri...