One of the things warren buffet repeats across his letter is his focus on limiting the downside to his portfolio. He considers a performance of -10% v/s -20 % of Dow better than a +20% v/s +10% of the dow. This clearly demonstrates the fact (which he has pointed out too ) that the portfolio was unconventional but also had a lower risk.
Warren buffet had put this approach in the inital letters and made it one of the key objectives in managing the portfolio.
The above approach bring to mind the quote from buffet -
rule 1 - Dont lose money
Rule 2 - dont forget rule 1
This is a very powerful approach to manage a portfolio. If one is convinced that the stock market would do well over the long term , and can limit the downside of the portfolio during bear markets , then as even buffet acknowldeged ,even if one cannot match the market on the upside , one should come out fine.