CZ was already successful before Bitcoin. He had advanced greatly in his software career and had even started his own company 4 years before Bitcoin was launched. His house was not his "wealth". It wasn't a case of a retail employee who sold the only property he owned to invest in Bitcoin, in a make or break financial move.
From all publications about him CZ was never one who valued properties like houses and cars a lot, Wich could have made doing away with the house much easier, particularly it he had wealth locked away in other different digital assets.
Also, your friend should definitely pay attention to the public, read books on investment, understand the risk from those that have been there, before making a decision. The market today and when CZ sold his house is a lot different, so you can't simply replicate what was done then.