Wow, Caspar, you sure know how to inflict suffering and death on sentient animals, and make inaccurate rationalizations for it.
Firstly, people should quit waiting until 6 months to spay/neuter. It can be done as early as 6 weeks, although some males don't descend until the 7th or 8th week, and then neutering can be done when it happens. There are no increased risks involved, and it's actually easier on the animal to have it done at 8 weeks rather than 6 months.
Secondly, really, that wasn't a very nice joke, even if it was a joke. While humor is subjective, from what I'm seeing, you're being inconsistent--were you serious or were you not?
Thirdly, I was NOT kidding when I said early sterilization is better for longterm health. If someone else had the choice of increasing or decreasing your cancer risks, and they chose to increase your risks, you'd probably be unhappy with the decision, particularly if it were for a trivial, selfish reason. Give your cats a little consideration--they don't want cancer any more than you do.
Fourthly, preferring STDs over a (very low from a decent rescue) risk of ringworm or something...no offense, but I don't think you should be permitted to have anyone dependent on you. Any decent organization will monitor health for as long as the animals are with them, and make sure to have them vaccinated appropriately and tested for disease before adopting them out. Having any old tom make Cammy sick is a good idea compared to that?
Fifthly, cats aren't just toys or tools for you to manufacture at will without regard for the consequences. You can go "hey, I want some more Pokemon dolls, I think I'll make some or pay someone to make them for me" all you want, but what gives you the right to do the same thing with cats? YOU wanted more cats, so you force the cats to make more FOR YOU, regardless of the harm it may inflict on them? Don't tell me that isn't selfish. Look at this list, and think of the ones that apply to cats and your situation: http://www.pbrc.net/breeding2.html
Sixthly, I'm sure the four cats that were put down in shelters because you wouldn't take them in are quite convinced by your nonsensical excuses. Every home that a bred kitten takes up is one that a homeless cat dies for. Taking in a few strays does NOT justify unnecessarily killing others. If someone murdered a person they had a disagreement with, then told the court "But there were FIVE people who made me angry and I did NOT kill them, so I have more than enough credit to kill ONE person, geez" I think no reasonable person would agree with them.
Seventhly, spay/neuter is not wrong in any way, unless inflicted on an animal in such poor health that anesthesia is risky, or deliberately done late! Not only does it save lives, would you like to see a list of conditions that s/n prevents or reduces the risk of? Here are some very uncruel things: testicular cancer, prostate cancer, prostate enlargement, uterine cancer, ovarian cancer, uterine infections, hypothyroidism, other endocrine dysfunction, breast cancer, prostatic disease, hernias, perianal tumors... As for the downsides, an extremely safe and minor surgery (stitches not even necessary for males), resulting in perhaps benefitting from one day of quiet. Which holds more weight?
Eighthly, going outside is extremely dangerous. Sure, in rural areas, there's a decreased (not zero) risk of car accidents and bunchers and such, but the risks of trouble with wild animals (fights, disease) also increase. Then you have poisonous plants, weather extremes, the possibility of getting lost, etc etc. With just a little effort on your part, you can keep indoor cats just as healthy, happy, and stimulated as outdoor ones.
Please take the time to think about my points objectively, instead of continuing to blindly believe that everything you do is just all sunshine and flowers.
In addition, I'd like to add that while recent figures are usually around 4 million animals euthanized in a year, this is a huge improvement over, say, a decade ago, due to aggressive spay/neuter campaigns. Before, the figures ranged from 8 - 20 million a year, with an estimated additional 5 million a year dying on the streets... This is around the time our wonderful, responsible friend here brought another four cats into the world.
I think most people can do quite well without your advice. People can consult a veterinarian, or two or three or more, if they want someone to talk to, and they can research the subject themselves and weigh the evidence if any doubt.