or what would you advice they do?
Based on my point of view, the next important thing you should use the profits that you get from Bitcoin investment after a long season of investment is to start a business or own a landed property. However Bitcoin investment is not like those things you mentioned such as business and trading, you invest and accumulate more Bitcoin so that you make huge profits in the future.
What is the next phase for a successful bitcoin investors ? or what would you advice they do?
one of the most common way a successful Bitcoin investor could channel his/her investment is by starting p2p as a fiat marchant on any of the top reputable crypto exchanges