Many years ago I took a class on handling a chainsaw. The instructor told us that two groups are subject of the majority of accidents. One are beginners because of their lack of skill. The other one are people who think they are experts. This group actually outnumbers the beginners.
When a person aquires a certain skill level that person may be tempted to take chances when the odds are unfavorable. Sometimes that person will lose. Sometimes you just get careless and neglect safety issues (BTDT <img src="images/graemlins/blush.gif" alt="" />, had luck so far). After a close shave you´ll be more carefull for some time. I guess that´s a feature of human beings. Maybe our odds for survival are best with a skill level just below expert.