Eh, youre not missing Much aside from setting flags and watching it compile. I don't think the performance improvements are significant enough at the point to bother. Though it was fun on some older systems.

Gentoo is fun to play around with but is not a daily driver at all.

Gentoo is a fun hobby tinker thing on some laptop you don't really care about. I will say kudos to people who do use it as a daily driver as they have way more time than I do and I envy them for it. If I had the the time to dedicate to it I would use it as a daily driver.