I completely agree that these things are oversimplified and people don't discuss luck enough. However, if you're able to isolate your retirement savings from the rest of your life (which is a big if which doesn't apply to many people!), things aren't so bad on a long timeline. Here are two data points that I find quite compelling. The first is about a theoretical person who saves money in cash between market run-ups and only invests at market peaks (spoiler, they end up with much more than they invested). The second just points out that the S&P 500 has never had a nominal 30 year streak with less than ~8% annual growth (which is not to say it couldn't).

http://awealthofcommonsense.com/2014/02/worlds-worst-market-... http://www.businessinsider.com/30-year-sp-500-returns-impres...