Is a leopard gecko good by it self?

By "on its own", if you mean in the wild, yes. They live in the wild about 8-9 years. But if you mean alone in their cage with no other geckos, they can, but they are happier alone rather than with 2 or more. If you are having 2 or more in the same cage, be sure that it is not 2 males, because they will fight. only multiple femals or a male and a female are safe together. (CAUTION: If you hav a male and a femal together in the same cage, they might mate and you might end up with up to 12 new Leo hatchlings!)