It's a lucrative business to be in. If you have niche technical competency there's a lot of funding to be had from companies that have problems to solve.
You're unlikely to hit millions like you would from a VC, but you can be solving very tangible problems rather than the stereotypical "Uber for X". And you would be amazed at how much companies are happy to spend on products that work.
I know regular custom software usually comes through the consulting channel, but i'm curious if machine learning and deep learning have gotten to the stage of maturity/simplicity that consulting companies offer them to their medium/small clients ?
I work in computer vision, so ML is kinda ubiquitous in the field and there are definitely startups that are selling deep learning as-a-service (canonical example is Clarifai).
The main issue with deep learning is that for a small/medium client, there isn't enough data to train on. Lot of clients want classification software of some kind, but often it's binary and you don't need anything as complex as a CNN.
There are a few big frameworks for vision, like Halcon, which include SVM and neural net implementations (and loads of other stuff). You can provide training examples and it'll do the rest for you. It's not cheap and you have to charge for licenses, but they even have their own little scripting language as well as hooks for C++. The idea is you can use any camera, drag and drop functions and get your solution out. I've never used it, but I've seen their sales demos and they're quite slick.
You're unlikely to hit millions like you would from a VC, but you can be solving very tangible problems rather than the stereotypical "Uber for X". And you would be amazed at how much companies are happy to spend on products that work.