You have done research on other investments and made good earnings from it. then this should be a problem when you try to invest in bitcoin. The risk maybe the same like stock but way more volatile on crypto.

and yes you can invest any amount or start from 100$ if you have a lot of money try 100$ first divide it into 4 or 5 and then start buying in on different time feel the volatility first and if you think is suitable for you, Go ahead top up a lot of money.