Uhanimar wrote:Geez why can't you just leave it be?
Because it is in your best interest to get it right. Not only do you avoid the risk of looking stupid, but always writing correctly in informal situations will make it easier and feel more natural to do so in formal situations, where it is MUCH more important.
As Blackthorne said, it really shouldn't be too much to expect proper writing from someone who has the language as their primary language when people with the same language as their secondary, tertiary or even n-ary language can get it right.
Of course, there are always exceptions to the rule. For example, no one would expect as much from you if you were dyslexic or had a different handicap of a similar nature. (And no, that's not a cue for ANYONE to wrongfully claim they're dyslexic just to get away with bad spelling.) Similarly, no one would expect as much if you were just 8 or 9 years old.
With that said, however, there's a big difference between misspelling a simple word (like stupid) and a difficult word (like Fhqwhgads). It's much easier to get away with misspelling the latter, because it is inherently difficult to spell. But because the spelling of the first one should be basic knowledge, you don't get away with getting that one wrong.