No, Nintendo did not buy Sega.
While there have been rumors and speculation over the years about a potential merger or acquisition between the two companies, they remain separate entities. Nintendo and Sega have been competitors in the video game industry for many years, with each company developing their own unique hardware and software.
In 2001, Sega made the decision to exit the console hardware market and focus on developing and publishing games for other platforms. Since then, they have continued to be a player in the video game industry, developing games for a variety of platforms, including PC, consoles, and mobile devices.
While Nintendo and Sega may have had a rivalry in the past, they both continue to be important and influential players in the video game industry, and their impact can still be felt today.