The truth is that probably most successful people can't tell luck, serendipity and hard-work from wisdom. Times change, opportunities change etc. so how much is advice really worth?
The only good advice is an answer to a specific question with very clear boundaries: "How much is a good amount to spend on Facebook advertising?", "If you have a product aimed at the mass market and you can correlate success of click-throughs, spend as much as you want as long as it's less than what you make per-click".
Otherwise you get stuff like, "Facebook is great value for money" or "Facebook is a disaster" both useless pieces of advice.
I also suspect that those with the correct brain for business probably don't need very much advice because they will quickly work things out themselves.