No, a 15-year-old cannot run out of sperm. The male body continuously produces sperm. Even with frequent ejaculation, sperm will generally always be present in semen.
Understanding Sperm Production
The human body, specifically the testes in males, constantly produces new sperm cells. This continuous production means that depletion is not possible through ejaculation, regardless of frequency. As stated in one source, "A man's body continuously keeps producing sperm and there is no running out of semen." [Source: Metromale Clinic] Even though a small percentage of males may have issues with sperm production, this is an exception rather than the rule. [Source: Medical News Today] Therefore, even daily ejaculation won't cause a 15-year-old to exhaust his sperm supply.
Addressing Common Misconceptions
Some sources address the misconception that frequent masturbation leads to sperm depletion. This is false. The body replenishes sperm cells continuously. [Source: WebMD, Quora] Frequent ejaculation does not negatively impact health, weight, or strength. [Source: Quora]
Conclusion
A 15-year-old male will not run out of sperm due to the constant production of sperm cells by the body. This is a normal and continuous biological process.
