No self respecting bigfoot would breed with anything that MAY produce a "rosie"
But seriously, I've spent LOTS of time in the woods of the pacific northwest. traditional "bigfoot" country. I find lots of carcasses of all the native species of large animals EXCEPT bigfoot. and nobody else has produced a single verifiable scrap of evidence either. No animal can completely dispose of its own remains upon its death. Any species needs to have a small population to continue propagating and a community of them that it would take to propagate would have been found. There are no places left in the pacific northwest that have not been covered on a regular basis by hikers and hunters.
They simply don't exist
The reason I love Cryptozoology so much is the same reason I love baiting Liberals so much as well. The mere inference that a Scientist or a Liberal DOES NOT KNOW EVERYTHING is enough to drive them into a foaming at the mouth rage. Christians are a small step below Scientists and Liberals. Very small step.
Anyway, it was only recently that a Cryptid, the Giant Squid, was proven to exist. For the longest time, the myths of giant squids were dismissed. That was until crypto's discovered a new species of baby squid. And then a very large squid was caught on camera. It was only after that was a body accidentally caught.
You're wrong in thinking you know everything, like you've clearly stated above. You're also wrong in thinking that all animals are automatons that just go through life to eat, sleep and have sexy. Research has been done to show that a few animals actually have cognitive thought.
On top of all this, we are still discovering new things about the creatures we thought we understood. Take the Brazilian rain forests. It was only just discovered recently that a tribe of indians existed that we never even knew was there.
With all of this, I believe the chance for bigfoot, and other cryptids, existing goes up. However, you will never get a Scientist or Liberal to admit they are wrong. You could slap them with a dead bigfoot's hairy palm across the face, and some would still not admit it.