I often see things that I think were done in a half-assed manner that are quite successful. I see people shipping things that I would never ship, and being successful at it. I'm not talking about spending inordinate amounts of time to get every pixel right (Though Apple may be a contrary example to my thesis here) ... I'm talking about spending an extra %1-%5 of time to make your site not be butt ugly.
I think PlentyOfFish.com is probably good example. He focused on different things and was a huge success. Its still ugly now, but it used to be, and for many years, was totally butt ugly.
Sometimes people of very average intelligence but great social skills do really well. Downright dumb people with the right personality -- e.g. the jocks who are now venture capitalists-- do better than smarter people.
This is an ongoing debate between my cofounder and I. Normally, my cofounder is the one putting forth this thesis.. the claim being that we're too smart to be successful. (Not in an arrogant way, there are lots of smarter people I know.) But I am starting to think my cofounder may be right. For instance, I do tend to over engineer, over optimize, and under execute.
So, our personal motivational theme these days is "just ship it". Can't fight the desire to make it not be crap, but we're shipping more.
PS-- another example of this is thinking you've got a key functionality right, because you're smart, you "know" this is the right way to do it, and then focusing on optimizing in other areas. So, you ship a game that looks gorgeous but has poor gameplay, or you completely miss the mark on the way your customers want to use your product because most people are not like you (because most people are average and you're not.) etc.