Well, it's a complex situation. Shigaraki dies as a result of a combination of factors including the coordinated efforts of the heroes and his own overexertion of his abilities.
Well, Shigaraki met his end in the manga after a series of intense confrontations. His powers were ultimately no match for the combined efforts of the heroes and the circumstances of the final showdown.
Shigaraki is not dead in the manga. The storyline has many twists and turns, and his character plays a significant role, so his survival adds to the ongoing drama and suspense.