There are two routes to build an AdWords campaign:
1. The fast and lazy way. You might come-up with an ad, loads of keywords, and throw them all just in a single ad group. Then, have your ads on Google all in about 20 minutes.
2. Or, you can go the more detailed route where you put your keywords into tight ad groups and create ads to split test in each. When you get an idea to optimize, you implement it.
Many advertisers may choose the first route because they don't know any better. However, other advertisers go with it simply because they think, "How much of a difference will it really make to put the extra work in? Won't I make money anyway?"
The answer to this question is it is possible to make money the lazy way. But, more often than not, you get creamed by the competition.
It's important to realize that there is space for a lot of advertisers. However, the top few are gaining most of the benefit. They may pay significantly less per click and generate far more targeted traffic than those advertisers on the tier below. It's the difference between making and losing money.
So, what's the difference between top advertisers and those who struggle?
The answer is they go the extra step. When they feel like being lazy, they keep on going. They make sure their ads are relevant, they have tight ad groups, their keywords are relevant, and they may even create custom landing pages for each ad group.
The bottom-line is the extra time you put-in doing it right is worth it. You go from risking it to giving yourself the best possible chance of success.