My first helmet (late 80s) was one of these- https://thecabe.com/forum/threads/vintage-cinelli-leather-hairnet-bicycle-helmet.101807/

Back then, you could choose between a lightweight leather Cinelli "hairnet" that offered almost no protection (but was race legal), or a heavy hardshell helmet that might protect your head, but was hot and really uncomfortable. These days though, most every cycling helmet is light, well-vented, and comfortable, so there is no reason not to wear one.