I was a pretty smart kid (still am actually. Ha!) throughout primary school, once I started secondary school things went a bit downhill. Started getting really lazy with my school work, did fairly well in my GCSE's but I could have done much better if I'd tried. Anxiety played a part in this. But that's another story.
For my Higher Education I went on to Sixth Form (rather than college) to do my A levels. Once again I did about average, could have done so much better, but it was enough to get into university and that's what I was there for.
Actually I wasn't. I was not interested in getting a job though, and I figured what the hell, might as well actually go to uni, could come out with a degree and much better job prospects. So I went to Staffordshire University to study Web Development, a bit of a lazy option since I was already heavily into web design and development prior to going to uni. And you know, it's not a particularly great uni, and I don't enjoy the course either.
It's extremely generalised and covers way too many areas of web dev - it is like they build us up as students to graduate as a "Jack of all trades, master of none" - this is not good. They should have a few select areas where we should be allowed to specialise.
That said, I'm in my final year now, and in a few months I'll be due to graduate. Once again with a fairly low/average level degree since I've been lazy. But, it might not be all that valuable to me anyway...
I'm optimistic about my life after uni. A few friends/contacts I've made while at uni may prove to be extremely good for me. In the past year I've got myself into developing iOS apps and have released one already. We have a pretty large scale app on the way too. Additionally, I'm busy with the re-development of a social network for filmmakers, one with great potential and lots going for it - the competition doesn't even come close to what we have to offer. The app and the website go hand in hand, so the popularity of one should lead to the popularity of the other. So things could work out pretty well for me.
So my advice from my experiences in my 22 years of life so far? Doing well at school will indeed help you, but it might not be necessary. Find something you're good at, and hopefully passionate about too, and just keep working at it. You can doss around in school, but not after that, so don't become lazy.
TL;DR - No, read my whole post if you want to know. If I wrote a tl;dr it would make my post worthless.