I have no strong interest in any particular niche, other than maybe embedded and graphics programming and those have a high barrier to entry. You generally don't find too many jobs much less junior level jobs in those fields.
What has happened in my career is, I have brought myself up to what I admit to be an "expert beginner"... through jobs that have been mostly lonely and unfulfilling experiences for a programmer (not a whole lot of experienced peers to network and learn from). So life has given me lemons, might as well find out how to make lemonade from them.