They say do not invest in what you do not understand which was largely the principle the speaker adhered to
That's right - I agree with his mindset.
but what if despite not immediately understanding the business model and its profit making model yet your business instinct pushing you to invest. What should you do? Listen to the former or follow your instincts?
Don't rush - you'll need to invest a bit of your time learning it rather than investing your money right away. The right course of action is that you need to learn and you need to know the ins and outs of the asset or project you want to invest in. Do your research and analysis - isn't that what always the experienced speakers on bitcointalk advise?
Following your instincts without knowing what prospects you will get from a project or an asset that you do not know about is gambling. You expect absolute gain without knowing how it works and what it's used for - it's the same as throwing money at the lottery without knowing exactly what number it will come out.