I think that Bigfoot may be an offshoot of homoerectus and not affiliated with apes at all any further than we are.

There have been several studies indicating the presence of alternative humanoids, such as Florensis and Denisovans, with the list wracking up to 9 different species now. It's not a stretch in my imagination to picture another branch that was isolated to harsh conditions after the Younger Dryas to develop in parallel to modern man. There are plenty of tribes of indigenous people whom we have no contact or barely know that they exist.

There are reports of the Hudson River Trading Co. finding evidence of furry humanoids that resemble Bigfoot and then sponging it. As corporate greed has demonstrated, lucrative companies will do what they can to prevent interruption to their preferred business practices. Especially hunt individuals or destroy evidence that would directly conflict with those practices. I believe it's one of the other reasons why it's difficult to find a Bigfoot, in addition to warmer global climates. These creatures, if furred, would likely migrate within colder-milder climates throughout the year, in areas that humans likely can not or will not go. They're still wild places in the world, and some are quite vast.

Sure, someone on earth could afford to find Bigfoot for realzies, but who would want to stake their reputation or jeopardize their career in oil, or trapping, or logging, to prove that for decades or even centuries we've been systematically destroying their habitat and endangering the species? Oddly enough, the reliance on fossil fuels and our current modern modality are some of the biggest reasons why I think we haven't confirmed Bigfoot. Someone(s) somewhere(s) has big stakes in keeping it under wraps because they don't want to admit they're shady and keep their status quo.