How much hair loss to see it?

Saw this online and how true is this? I get that many people are not as concerned with their hair like us in this sub and never track their hairline and density until they one day look in the mirror and realize they’ve lost a lot. What about guys who constantly monitor their hairline, take pics, compare to old photo’s, i.e really track everything regarding their hair. I for one do that and still...

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