Its niche because the idea can be easily replicated by the incumbents in the industry. And it will be hard to scale at a global scale because the perception about ex-cons varies a lot in different countries.
As such the profits wont be able to keep up with VCs expectations if they invest 100s of millions of dollars. OP has a great first mover advantage and knowledge of the market, and they can capitalize that but the idea isn't worth billions.