First of all, something you see every day does not look big to you, it looks normal. A larger than average penis only looks large in comparison to average size ones.
Today there is more opportunity for a young guy to view a wide variety of penis sizes which is good and bad, and there is abundant information and misinformation available regarding average size. When I was growing up, unless you were in the habit of deliberately comparing penis sizes with other guys (which I was not) the only visual comparisons you got were in group showers or perhaps seeing your father or brothers nude. Most young fellows first saw a fully developed adult penis on their father or an older brother and felt very small in comparison.
Those penises one saw in school gym class locker rooms were generally flaccid so one really had no good idea on erect size. Furthermore, there was always a guy or two who went through puberty earlier than the rest (you assholes know who you are) and were thus significantly bigger than guys a grade or two ahead. Couple this with the universal tendency of young men to grossly overestimate their penis sizes and you could have been a teenager with a seven or eight inch long erect cock and still have felt average, at best.
Even if you were reasonably confident that you were at least average, the knowledge did not necessarily instill confidence in dealing with members of the opposite sex.
