20% ROI but not a stable business. what should i do?

I am running a business of my own that it brings me more than 20% ROI everymonth. I see my bank account is growing quickly. I invest every single dollar i have into the business to make as much as possible. I know this is just a quick cash business, it has been going well for the last 3 years. However, I want to use the cash I have to invest into more a sustainable business. Don't get me wrong, i am extremely happy and grateful for what I have. I try my very best to keep up with the business. Should I keep focus on what I do and try to make the most of out it? and at the same time looking out for some new opportunities? i have been searching around on what to do next, but I am clueless. I have a finance degree. And I do not have any coporate experience. I work for myself since I was 19. And I am... under 25 at the moment. Any advice on what to do next? how to manage the liquid i have to keep doing what i do and still have some smart money to invest on something at the same time? how to find a new trend?