There's a famous story about a Marketing Executive who makes a mistake, costing his company 20 million pounds. When he asked his manager whether he was going to fire him or not, his manager replied "Why would I do that, when I've just invested 20 millions pounds in your education?"
The saying goes making mistakes isn't criminal, making them twice is. In marketing, and in business in general, it's extremely important to learn from your mistakes, and the mistakes of others, and ensure those mistakes aren't repeated.
The largest companies have made huge mistakes, but the reason they're in the position they are in is they learnt from them. If that form of market research didn't work before, don't try it again, at least not in the same way. If those customers weren't responsive to your product, find a new range of customers to target. If noone responded to advertising in that new form of technology, find a new one.
The cost of your mistakes has an incredible return on investment, so long as you learn from them.