On the one hand, it’s a shame that it’s not open-source, but on the other hand, developers have to make a living from something.
I'm pretty sure most people here, at least I hope, who use open source and free software directly money donate to developers. I know of plenty of developers who do get paid writing open source through such donations or via funding, e.g. NLNet or grants. Maybe I'm misunderstanding your statement, are you saying Sublime Text isn't open source because they believe those ways are not appropriate for them?
Right indeed, not sure why it was implied that open source software couldn't be a financially viable option for developers too.