"If a character is immortal — even if it's the "immortal but can die temporarily" type — then their opponents don't need to hold anything back. Not even if those opponents are good guys. IMMORTALITY IS A SWEET GIG. Whether it's because the character can download into a new body as part of a Hive Mind, has a Healing Factor strong enough to reconstruct From a Single Cell, or possesses some even stranger way of staying among the living. The downside is everyone else now considers you fair game for target practice."
What does "a sweet gig" mean here?