I'm really glad you asked this question!

I got accepted into an accelerator for Somma by explaining my reasons as to why Somma will be free. I was asked why by an investor at my interview and I gave her and answer along the lines of "My goal with Somma is to pigeon hold the competition by offering the same product for free offering and extremely enticing front to steal their users." of course this will cost money and I admitted that to the investor but I said the payout from an acquisition will be worth the risk. I and where Somma is located is in Australia so our market is a lot different than the west and Europe.

That being said, I am a logical thinking founder so I have two other business models in the event that our investors want revenue. The second model is using investor money to acquire a company that will essentially be the cash cow for Somma so that we can keep it free, A lot of larger companies do this it's called a float. The third model but not my favourite is implementing a plan/subscription model.

I'm a management and finance major so while my technical knowledge may simply be enough to manage a bunch of engineers my business knowledge is more than enough to work with investors.