I think it is naïve to expect bigfoot to be more neighborly to humans than humans are to humans.
It may be that most of the time, when things are hunky dory, there is no need for conflict and there is no conflict.
But there are times when they may perceive a need to protect young, or females, or food sources, or territory and things can get dicey.
And there may be times when food is genuinely scarce and the stray human is a viable menu item.
Hominids have always competed against other hominids, just as different groups of humans compete against each other.
And why are bigfoot so big and powerful? I'll wager that it isn't so they can be cuddlier for our sakes. Lots of people would love to hug a polar bear and I'm sure there are lots of polar bears that would love for them to try (I'm actually in favor of allowing anyone who wants to, to make the attempt).
I'll also wager that bigfoot understand the relationship between humans and bigfoot better than we do. And if we can attribute intelligence as a factor in their perceived lack of harm toward us, I'll offer that they either understand the downside to preying on humans and choose not to do so, or they choose to cause harm only when they are sure that they won't get caught.
And then there is always the bad tempered rogue who may have had a bad experience and nurses a grudge.
Bottom line is that they don't prey indiscriminately or everybody would know about them, and there's no reason, other than crunchy wishful thinking, to believe that they are all benign and never harm people.
In my opinion, any one of them is capable of violence under the right circumstances and is built to be devastating.