Saying there is no fossil evidence without even knowing how close a bigfoot is to a modern human isn't valid. Is it supposed to be a valid argument that because they were labeled as erectus that they therefore aren't bigfoot ancestors? That is assuming way too much information from a few fragmentary bones in the majority of cases. It is also assuming way too much about what people think they know about bigfoot. Even in the best cases you don't know how "human" any of the erectus were. That is a subjective opinion and much of it in the past like why they were all called erectus has been recently shown to have been invalid. They weren't likely the first to leave Africa. New fossils have demonstrated that the ancestry and therefore what Asian erectus were is not certain. Not only is it not certain, it was pretty obvious from the evidence even several years ago that some Asian "erectus" were not likely very closely related to modern humans. They had features like enormous jaws, reduced frontal lobes, double occipital crests on top of their heads...
Some from the last million years seem to be much closer and probably related to the group that includes early heidelbergensis. There were apparently others in Asia though.(ancestors of floresiensis for example) Lack of recent fossils doesn't mean they went extinct. I have to assume from some attitudes that some people think lack of fossil means they went extinct. Did they in reality suddenly expand into several new species in the last several years or were we just ignorant before. There is no reason to expect that science now has all the species nailed down. It begs the question, what would a bigfoot fossil ancestor a million years ago look like? Assuming that it has to be 8 feet tall doesn't even exclude all "erectus" if you accept the physical anthropologist Krantz's estimation of some of their heights. Inhuman features? I already covered some of that. A better question is which of the erectus in the group called meganthropus, for example, isn't a bigfoot ancestor. I expect the answer to be in the form of "because it is erectus" and "they have fire and tools because they are erectus".
People need to reorient their beliefs to incorporate the reality that multiple species/populations existed in the past and how that makes it probably unlikely that they were all technological. They weren't all on some mission to become modern humans and assuming they acted like or had the same niche as modern humans is just wishful thinking and not a logical assumption from the point of view of simple biology. Radiations of new species generally involve new niches and some form of isolation. People really shouldn't assume that common perceptions of what any of the hominids were actually like is necessarily correct. That especially applies as you go back before a million years ago and when there are multiple species. Since there have always been multiple species until fairly recently, it should logically add doubt to how they lived since you can't usually assign tools to ancient bones with much confidence, for example, if there are multiple species. That concept is not simple. For example, it breaks down what people think they knew about habilis as being technological. You wouldn't know if another like rudolfensis made all the tools. That spills into the uncertainty of some Asian erectus since you can't differentiate which lineage they belong to. That is just assuming that you, for some reason, think they can't lose technology.