Instead of saying I have my own house or I have my own apartment, I have heard the words 'I live by myself'.

I have heard these things from the people whose mother toungue is not English.

I think it would incorrect to say 'he lives by himself' to convey you the message that the person got his own flat or house.

Your thoughts, please.
Quite so.
"I live by myself" means there's nobody else living with you on a regular basis.
I take "You live by yourself" as "You live alone without assistance from other people".

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By oneself means "alone", it doesn't imply that you own the place.
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