I get the biggest giggles when I come across people that say I developed a million dollar product. I ask them how they know and they say that there friends and family love it. WHAT? Are you really going to rely on the words of your friends and family to tell you that your product is great? What about the other 327 million other people that live in the USA? Market research is a vital part in creating a successful product. What goes into market research? You need to understand the trends and who you want to sell to. You need to ask yourself if you are solving a problem with your product or service. Why are people going to buy your product? You need to identify where your customers are. Do they only buy on the internet or do they only buy from a big box retailer? I would say most important is you need to know if your potential customer can afford your product.
I find that many do not perform the research because they say it is too expensive. However, when they goto market and have an epic fail they ended up spending much more money then what is cost to do some market research.