Concept design is a big area that deals with other areas. But it stops a step before planning starts and always remains a bit ephemeral. Deciding to bet on yourself and base your concept design career only on this phase can create many problems.
I have 8+ years of experience in designing, and I build a career using only concept design which was my mistake because nobody wanted to talk with me or saw my portfolio. They asked only one question: “Do you have more real works that we can touch?”.