There is no wrong concept if you talk about Bitcoin Investment unable to lose and be able to lose both saying is true, it's just that we must understand from the meaning of the two concepts.

Unable to lose: the meaning of investors is not recommended to invest by selling all their property assets, such as selling houses, borrowing at banks and so on that can be at risk for themselves in long -term investment.
Able to lose: it means investors if investing activities are encouraged little by little.This means you set aside at least 30% of your incomea Investing in Bitcoin, of course the concept is not too risky in the long run if the price of Bitcoin falls and rises for a long time.

Conclusion: Both sayings are both true and have the meaning of how to carry out Bitcoin investment activities.