As has been stated, I doubt that any increased hairloss due to exercise would be worth quitting the gym for.
Honestly, if you're going to be losing hair, the best thing you can do is take care of your appearance in all other ways:
1. Care for what hair's left. Get a nice cut/color and be sure it's always clean.
2. Keep your skin clear and clean, and get your teeth shiny and white.
3. Dress in clothes that give you confidence and look good on you.
4. Work on your conversation skills.
5. Hit the gym!! A good physique can make up for a little hairloss. My best friend has thinning hair and a receding hairline and still manages to pick up beautiful women. His secret? He's in great shape, keeps what hair he has shaved (he's been doing that since before he started losing hair), dresses well, and carries himself with confidence.
You could always do what I'm trying: I'm starting a new workout plan soon, and taking care of the hairloss problem with a hairpiece.
It's the best of both worlds, in my humble opinion.