Everything depends on your goals, scale, and budget. This is because you'll have to pay for plans on AI websites for high-quality videos.
The combinations used are completely different. If you invest time and pay for a subscription, you can create a full-fledged movie.
If you just need a talking avatar, you can create it in ChatGPT, for example, and animate it in HeyGen. Alternatively, you can use Synthesia (this is more for a business style). In simple terms — a talking business head )))
You might also need tools for audio processing (for example, if you want to use a specific voice or have the avatar speak with your own voice).
Regarding making money, it's better to focus on the process itself as the goal. Because it's unlikely that a character will generate income in just one day. There are stories where people simply published YouTube Shorts, gained subscribers over a year, and only then started monetizing.
First, define what you want to achieve in the end. Then, make a list of the necessary tools and go ahead — conquer the vastness of the internet media space)