Powder-keg ideas are very rare. Yet I get many cold pitches promising them. "I just need some investment to launch."
Since the probability of actually coming to fruition is so low, a powder-keg promise (without any evidence) leaves me placing you in a bucket with people you probably don't want to be grouped with.
In other words, it's counter productive. It's also counter-intuitive. If you truly have a powder-keg idea, you should be doing everything you can to launch without formal investment because the second you spark that powder-keg your valuation will skyrocket. Traction trumps everything.
My advice would be to take a step back and write down all the underlying assumptions that lead you to believe you have a powder-keg idea. How and why exactly will you achieve viral growth? Literally break it down by the numbers.
Then see if you can prove out those assumptions as cheaply as possible without investment. Maybe you can nail down some of them, or at least place smaller error bars around them.
Then temper your message a bit and let people like myself extrapolate as we see fit. That is, under promise and over deliver.