I don't think a store selling $20 gallons of cow milk in slightly prettier packaging than Fairway does becomes more reasonable or less surprising just because you specifically happen to be in the cheese industry; your salary or field is a very small bit of this specific discussion imo.
ITEM : ITEM OWNER'S SALARY is not the most useful metric to determine whether an item's pricing model is fair; ITEM : OTHER ITEMS OCCUPYING SAME MARKET NICHE, ITEM : OTHER ITEMS SERVING SIMILAR DEMOGRAPHICS, etc. seem more helpful for the discussion for the whole community. I've justified buying incredibly specialized tools because I'm a Venetian glassblower by trade, but at the end of the day they're still $400 scissors. My ability to justify, afford (or write off) the cost of something doesn't retroactively affect the cost of the item for everybody else.
To answer the t.c.'s question, I honestly think the broadest and simplest answer of "Because there's nothing stopping them from charging you $60, but there's also virtually nothing pressuring you to pay $60" is the reason why the devs can charge that much when gedit offers similar syntactical awareness and highlighting, and .xml themes, and vim offers a similarly community-developed platform for plugins (or two, in vim's case).
If Sublime constantly showed pop-ups interrupting your work onscreen, or limited your ability to save, or even attempted to justify the cost with a bunch of poor-me, it cost $x to develop this and $y to develop that...nobody would feel the urge to support them, small/indie company or not.
They've hit a really good balance between self-confidence ("we know we're charging more than others because we think we've made a superior product") and humble self-restraint (they don't spam for donations, they respect your workflow, they request but don't guilt or demand) is the only reason people are willingly paying and not regretting it.
There are times when splitting a fullscreen terminal, switching over to zsh or fish, and opening vim and pearl plugins, serves me way better than opening up Sublime, and all of that stuff is more feature-rich and cost-free, but ST3 is still one of my top purchases this year because it's polished, functional, helpful, pretty, and most of all apparently made with pride by people with good heads on their shoulders.