Can one start balding in their 30s or 40s?

I have a friend who just turned 36, who says that he had a “thinning” phase when he was around 22-23 where he said his hair noticeably changed in texture (became thinner and weaker). He’s not on Finasteride or anything but for some reason his hair loss essentially stopped and he hasn’t receded or thinned any further. Is this possible?

Yes, people can start balding at different rates and at different ages. Some men may not even start until they are 50 (unusual but it does happen).