If you’re 25, you might as well spend your evenings trying to upskill. Make time for important things, but trim unnecessary leisure and invest in your skills/expertise/network. It’s much harder to do this when older.
Personally I continued to improve my technical skills, especially in getting into new areas like AI, while also building considerable domain knowledge, and taking on management responsibilities. You don’t really have to compete directly with yon 10x STEM rockstars - go for breadth, not proficiency. Someone who understands a lot of areas fairly well, and can communicate and document well, is incredibly useful to an organisation.