That is true. Is a safe deposit box a good idea, then?
I would think of it in the same way as I would the value in cash. If say it was 1 BTC where would you feel safe storing $8,000 in cash? Maybe a decent fireproof safe at home would be ok but for 10 BTC or $80,000, I would go for a safety deposit box. That's an individual opinion on risk tolerance, everyone will have there own view on that.