I understand where you're coming from, I just don't get *why* people (not only you) approach remarks in a profile from the serious side. A comment like the one mentioned in a "tell something about yourself" section of a FB profile sounds pretty harmless to me. I take it as an attempt to make a funny statement. Maybe at most an overstatement to be interpret as "don;t mess with me, or I'll block/de-friend/ignore you." But certainly not as a threat to physically beat me up. I see it as nothing more than that $150k everybody seems to be making ;).
*insert "you only make 150k a year, hey, I make XXXXX"-jokes*
When somebody would start yelling stuff like that in a discussion, I'd take it he's a bad debater, and has to resort to an attempt at bullying in order to make a point. Still, I'd not see that as a physical threat.
What I'd like to know is when people started to take all that stuff so damn seriously. People lie, and try to impress others. It's human nature, live with it. Either it's driving a bigger car than you can reasonably afford, lying about your income in the singles-bar or putting statements like "I'll beat your ass into submission" in a facebook profile.
Personally, I think it's one of the charms of the internet. Strong statements bring a bit of panache, without bringing any real harm whatsoever. (Other than a bruised ego) Besides that, the problem with assuming people will interpret your comments for the worse, and adjusting them accordingly, is that you'll end up with a big goo of blanket-statements, because everybody is just too afraid to say anything that might even remotely offend somebody else. I prefer to assume strong remarks are harmless, unless I have a very good reason to believe otherwise.