The idea of having something living off of you never really appeals to many, but sometimes having a 'hitchhiker' has it's advantages. It might be more power, improved abilities, maybe even prolonging your life, but there are usually some setbacks, and it might even take control of you. A good example is Spider-man, Spider-man encountered the symbiote when he was on a alien planet. His costume was badly ripped so he decided to make a new one like Captain America. However, he did not see the machine Cap used, so he accidentally released the symbiote. The symbiote gave Spidey Enhanced strength, speed, agility, durability, endurance, and organic webbing. Since Spidey is only 16 this is a major thing for him since he does not have organic webbing. So Spidey enjoys it a lot, however the "hitchhiker" if you want to call it made his personality change and it fed off of his hatred and anger. So usually having the "Ultimate power", is only good for a short time, but sooner or later it will control you in the end.