Wow it's surprising how much hair you lost after your 20s. I would have thought you would have been losing more of it sooner than that. I mean, you had chest hair there and everything too. Usually once a man has his body hair and facial hair thicken up, it seems like they won't lose much hair after that point. Guys who haven't "matured" yet and are destined to gain more body hair are usually at risk to lose more hair as they have yet to have more androgen receptors activated. Your case is just bad luck really.