Raising offspring presents a huge cost to the parents, but every living organism does it because it's the only way to ensure that your genes will propagate on to the next generation after your death. Those that don't are washed out of the gene pool, and irrelevant after one lifespan.
Similarly, death is obviously bad for an individual - it's the termination of your existence. However, it frees up resources for new individuals who may be better adapted to conditions of the time. Species where individuals rarely die may see the whole species die off at once as they get outcompeted by other species whose individuals are better adapted to the environment.
(There's a societal analogue as well here: historically, societies that hold tight to tradition and preserve the internal firms & institutions within them end up being conquered, en masse, by more competitive societies where the individual firms within them either adapt or die.)
Similarly, death is obviously bad for an individual - it's the termination of your existence. However, it frees up resources for new individuals who may be better adapted to conditions of the time. Species where individuals rarely die may see the whole species die off at once as they get outcompeted by other species whose individuals are better adapted to the environment.
(There's a societal analogue as well here: historically, societies that hold tight to tradition and preserve the internal firms & institutions within them end up being conquered, en masse, by more competitive societies where the individual firms within them either adapt or die.)