Should you start a product company or a service firm?

I was having the 'product vs service startup' discussion with a colleague yesterday and how entrepreneurs should adapt their thinking based on life-stage and risk appetite. The holy grail of a product startup is the elusive 'product-market fit' after which revenues can grow exponentially like Uber or Facebook. However, the probability of achieving this fit is really really low, even in niche B2B areas (think of all the expense solutions and marketing automation products out there). Some of us entrepreneurs in our late thirties may not be able to afford jumping from one failed product to another. We need to grow revenues with predictability, which is what a service business allows you to do (relatively speaking). However, productizing portions of your business internally is a great way to achieve some non-linearity in growth. It can help cut costs, while still keeping customers happy.