To me an SaaS is company that solves one, maybe two problems that a customer would rather pay money to solve rather than develop their own solution, and more often than not those solutions come in the form of an API.
When I look around for problems in need of a solution, I can easily identify them, but I don't know how to tell which ones are worth pursuing. Either because the problem itself is extremely specific, or someone has already thought of the exact same solution I came up with and already has an business set up around it with paying customers.
It feels like every problem that's worth pursuing has already been solved and commercialized.
(2) I don’t know where you are exposed to it but you see a lot of stuff about “passive income” online that I think is misleading. For instance you could get “passive income” from renting an apartment but you have all kinds of hassles to deal with and if you pay a property manager to deal with those hassles for you they’ll eat your profit. The people I know who make the most profit with rentals have blue collar skills and they will go fix a leaking toilet themselves when a tenant calls at 2am.
Right now I’m planning to develop and market a product which could make me and a friend some money in royalties, really I am doing it for the fun of it and I would not mind at all if I lost a few hundred dollars pursuing a glamour profession and had a great story to tell in the end. That’s how I look at those kind of projects.