I would probably sell under one of the following scenarios: 1. When you are bored of what you are working on and a sale would net you enough money to live for

I would probably sell under one of the following scenarios: 1. When you are bored of what you are working on and a sale would net you enough money to live for enough time to startup one or more new venture(s) that you are interested in. 2. Not bored of the venture but think that in the immediate future your business might come under attack by an incumbent and you are not agile enough to fend off said attack. Note: those are just two that I would sell off under. I am sure there are a few more that would be a good time to sell but I am not able to conjure them right now. I would also wager that you should be able to get a fair sale price given the growth metrics you are using.(As long as they are not too cooked.)