You have veins because you have a genetic predisposition to leg enlarged veins. Then with the right life circumstances the pressure in the veins build up. You cannot cure the varicose disease, but you can treat the vein and alleviate symptoms of dragging, swelling, pain and aching.
Both types of veins on the legs, "varicose" and "spider" can be treated and most will respond to injections. Even the largest veins will resolve with persistence and without the need for surgery using ultrasound guided Sclerotherpay.