Take your current expenses and reduce them by 40%. Figure out the age that you would retire regardless of whether or not bit coin continues to succeed, find the most conservative 20 year forecast you can find for the value of the coins and divide by 5000%. I think you can see where to go from here? Find the amount of monthly income you need (with a 40% reduction from what you would need now in a restful period of time.) and calculate it on a lower than your most conservative calculation basis. Don't include BTC speculation in any insurance or medical expenses you plan for. Don't include it in any major milestone vacations you plan to take. The Bitcoin aspect of your investment portfolio is a lot like playing casino dice games to pad your retirement. It's entirely subject to failure as is any currency, however currently lacks the simplicity of a universally accepted fiat currency, unfortunately. Planning for the most conservative scenario possible will give you a realistic perspective for your future.