Based on my cheatsheet, GNU Coreutils, sed, awk, ImageMagick, exiftool, jdupes, rsync, jq, par2, parallel, tar and xz utils are examples of commands that I frequently use but whose developers I don’t believe receive any significant cashflow despite the huge benefit they provide to software developers. The last one was basically taken over in by a nation-state hacking team until the subtle backdoor for OpenSSH was found in 2024-03 by some Microsoft guy not doing his assigned job.
“That all life beyond this planet never existed, no matter how irrationally improbable that may be.”