Why not tell anyone?

I noticed on a couple posts around money career success etc on this sub that many commenters from this community tell an OP who might ask about investing or their savings or wealth gains etc to ‘not tell anyone’ about it.

I’m so curious as to why so many of the older people here advise that… and also wondering if it’s all about a kind of ‘tall poppy syndrome’ or other wise reasons?

Please elaborate on this wisdom!?

Also - is it ok social etiquette to ask someone if they paid cash or got a loan for purchasing a new property ?