Most people in tech are not making $500K to write Javascript or anything else. And, even if you make a fair bit of money, $3K isn't a trivial sum to make even 12-16 hours of air travel a bit more comfortable. (It still isn't exactly fun even up front.) I do sometimes use miles and a co-pay to upgrade when I can but, generally speaking, I can get a lot more bang out of that money on other things whether meals or other experiences.