The biggest ROI is fulfilling my childhood dream of having a ton of my favourites rare plants. Then I sell my extra ones on my webshop, but it doesn't make that much money as I am not focusing on expensive varieties, just the ones I like.
You can check out plants in jars on YouTube, or use a LLM to get into it. Some LLMs might not want to answer you because they think you're trying to do something dangerous... Claude has been flagging a lot of my questions.