I don't have many years experience trading and investing but, like you, had money to invest after selling a property. I wasn't at all satisfied with the 6% a year return that I was being offered and believed I could do better on my own. I have a high risk tolerance and managed a 40% return on annual basis over 2 years. But reality is my return in year 1 was 80% and year 2 is 0% (still working on improving that). I'm lucky, I haven't lost any money yet. Maybe in year 3 I will, or maybe I will do really well, but I don't know. Personally, a conservative investment that many would think is not is to put 25% in Google, 25% in Amazon, 25% in Apple and, for the risk, 25% in Tesla, then forget about it for 10 years.
Actually your return over 2 years is only about 34% per year. The magic of compounding works both ways.
I would have to ask what you mean by a long-term investment. For me that should mean an investment with a holding period measured in decades, not years: plus one which you can will to your children. Shares have the advantage of paying a dividend which you can cheaply re-invest into the same stock. Some long-term investors just hold the biggest 5 listed companies and re-invest the dividends. You can juggle with this portfolio and its relative proportions but that should be a rare event. I wouldn't recommend much attention to diversification in long-term holdings. If you want a higher return on capital set aside 10% of your pot for active trading (if you have a consistently profitable trading strategy).
Buy SPY (or VOO), QQQ, and/or VONG in some fixed allocation, and hold till your retirement. Use the portion of your account you feel comfortable with allowing it to ride through market gyrations. This pullback presents a decent entry point. (Market timing best left to someone who thinks they have it perfected)
I'd add my two cents. Take out of the money and pay a quality investment/financial advisor to guide you on what to do.