Why would this be the method of "highest returns"? Remembers that brokers are on the sell-side. Their business model is selling investment products for commissions. It might be the method of lowest returns if you ask me.
Now if you invest using into a hedge fund which trades Bitcoin you might have higher returns if they have a proven track record, but they too take performance and management fees from your funds and profits.

I think is well-worth it in the long run to invest in your education and take responsibility for your positions. Just my 2 cents.