The hard thing - and cool thing - about launching a startup is that every component is a risk: am I building the right solution, will customers find me, can I find a team. What if this doesn’t work? What if this DOES work? As inherent risk is to a startup, not surprisingly investors don’t like risk.
Early on, identify the biggest risks for your company and address them head-on. For example, test customer acquisition with an ad-driven landing page.
What hypothesis, if proven false, would cripple your startup? Start there.