So I'm neither a marketing or sales guy, though I have done a bit of both.

What I'd say is that if you are trying to create a successful business / product ... you need to be considering marketing/sales before you actually build anything. The classic tech founder mistake is to build something nobody wants. Or that costs more to produce/support than you can sell it for.

I've got a funny story about a dotcom era business I worked for, where an amazing tech team built this product that was miles better than anything our competitors were doing. We spent 18 months getting it all built out etc. And then the business guy came in and ran the numbers and pointed out to us that our return on investment was longer than the replacement cycle of our hardware. Oops ..