How common is it for somebody to get fungal infections?

Very common. Jock itch and athlete's foot are both fungal infections; both are very common. The deeper (and more serious) fungal infections are far less common in the US, but relatively common in tropical countries, particularly in areas where poverty and malnourishment are also common.
Foot fungus. Fungus occurs commonly in humid, warm regions.. It may be athletes feet & toe nails, or jock itch or on the body, face and scalp. There are some fungus germs that attack people and some attack dogs and cats, and some both. Some people have a family tendency to get foot fungus. Some fungi, called yeast, can grow in the vagina and come from taking antibiotics or birth control pills.