Most adults aren't mature enough and don't appreciate the risks they are taking. If they did, Jerry Springer wouldn't have stayed on the air these last 20 years. I don't think I've ever met anyone who wished they had waited longer to lose their virginity or wishes they hadn't fucked so much on their deathbed.
If the question were purely biological, interest in sexual pleasure doesn't begin at puberty. There is plenty of scientific evidence that humans are fully capable of orgasm from conception on. There is ultrasound footage of fetuses masturbating in utero. The only thing puberty changes is