Cacti are succulents that retain water in their thick petals and stems. This doesn't mean they shouldn't be watered properly though.
There are several factors to consider:
1. What type of container is the plant in? Is it small and shallow or large and deep?
2. Is the plant in direct sunlight all day long? Cacti can handle this but the soil cannot. The soil will dry out more quickly and will require more watering.
Soil for cacti should not be too wet, for sure, but that doesn't mean it should be bone dry. Take cues from the plant itself. Withering is a clear indication that something is not right.
Google some info about cactus care. There are different types of cacti with varying needs.