1.) Single Founder
2.) Bad Location
3.) Marginal Niche
4.) Derivative Idea
5.) Obstinacy
6.) Hiring Bad Programmers
7.) Choosing the Wrong Platform
8.) Slowness in Launching
9) Launching Too Early
10.) Having no Specific User in Mind
11.) Bad Customer Service
12.) Raising too Little Money
13.) Spending too Much
14.) Raising too Much Money
15.) Poor Investor Management
16.) Sacrificing users to (supposed) Profit
17.) Measure the Wrong Things
18.) Not Wanting to Get your Hands Dirty
19.) Fights Between Founders
20.) Half- Hearted Effort
J’aurais mis ça en #1 
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on sent l’expérience 
By the way on aura reconnu la version vidéo de l’article de Paul Graham http://www.paulgraham.com/startupmistakes.html