Most people drastically underestimate how big a 7" penis is. Statistically it's about 1% of the male population or less. A 7 incher will probably bottom out 90% of women, and cause pain to many of them.
I'm 6", measured with a ruler.
Every woman I've ever been with has told me I have a "big dick" or a "huge dick". About half the women I bottomed out (in certain positions), and about 20% bled after I had sex with them the first time (not on their period).
There was one woman I literally couldn't fit inside. Her vaginal opening could not accommodate me.
I had one girlfriend take me to a party wearing baggy shorts and encourage all her lesbian friends to grab my "giant dick" through the fabric of my shorts. Again I'm only 6 inches long but she though it was noteworthy enough to brag to all her friends about how my penis was the biggest she'd ever seen. She had been with a lot of guys too.
I've asked a few women how big they think I am, they generally think I'm about 8" long because they've been lied to their whole lives.
The average male is 5", but thinks they're bigger. 7" and up is extremely rare. Most of the dicks you see in porn look to me about my size, 6".