very valid point- but people do start with passion and iterate being the keyword based on understanding users and the market - however if you jump straight into competition/market without having interests or passion then you are driven by numbers and other people and have nothing to fall back onto in terms of purpose/vision/mission - so someone passionate in ornamental gourd futures can use the passion in it to underdtand other peoples/passion or interests in it and then in the process develop your understanding of them to feed what they are looking for coming from your evolved passion now - youtube was hotornot pics to begin with!