You shouldn't ignore them. If the odds are bad and you only do it for the money then don't start a business, you'll just make yourself unhappy. Start a business because that is what you want to do, then the odds doesn't really matter because you aren't doing it for the money. Or because you have a good reason believing that your case is special.

But absolutely don't believe your chances are great for no reason as the self-esteem enthusiasts would tell you. I see countless people wasting their life away chasing ideas just because their self esteem is way too high. Don't do that.