So, an interesting thing I observed while building a SaaS company was that you can actually get off the ground with a very simple solution, you'll just end up serving smaller customers with relatively simple needs (say $50-100/mo.) These initial folks will pepper you with feature requests while still paying you money for what you've got, which can give you feedback about which complexities you're missing that you really need to implement. If you choose which things to implement carefully, you end up making your product more useful to larger customers and you'll start closing some larger deals. (E.g. $500/mo.) Rinse and repeat and before too long you've got a product with all the bells and whistles and you're closing enterprise deals. (E.g. $2,500+/mo.) The numbers here are all relative, but the point is that the smaller customers end up subsidizing the development of what becomes an enterprise product.
(I think the advantage this approach has over the one you've suggested is that the product is always capable of making money even from the very beginning, just on a smaller scale at first. I think this is a critical feedback mechanism so that folks know whether what they're developing is actually useful to folks.)
Great comment. In a way, it's like what Geoffrey Moore talks about in his book "Crossing the Chasm", about the difference between early adopters and mainstream users.
(I think the advantage this approach has over the one you've suggested is that the product is always capable of making money even from the very beginning, just on a smaller scale at first. I think this is a critical feedback mechanism so that folks know whether what they're developing is actually useful to folks.)