Empires are built on top of old, ugly, or niche technologies. You might have more job opportunities with the latest and hottest tech, but you will have far les

Empires are built on top of old, ugly, or niche technologies. You might have more job opportunities with the latest and hottest tech, but you will have far less competition with legacy ones. And you can have a long and successful career with them. If anything I would consider a red flag to have proprietary or in-house stacks. Those could damage your career by employer lock-in, where your build expertise in tech only used in that company, thus reducing your marketability.