I would say he has Telogen Effluvium. No normal person visibly sheds 300 hairs a day (probably closer to 500 if you want to talk about the hairs the randomly fall out during the day that are not counted.). Nor should the rate of shedding be increasing.
OP is being judged by his initial pics but the ones he has posted since show Telogen Effluvium like diffuse thinning.
This is still a pretty good head of hair at 40 but the pics demonstrated that he started with initially showed an unusually, incredibly thick head of hair for his age bracket.
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