The question you need to ask is can this security support a billion dollar valuation? The sector needs time to mature so the market can properly value each company. Your question is good and to your point no MCIG cannot support a billion dollar valuation today. Book value doesn't support what's currently being priced in by the market.
The company could be better capitalized imo but management is strong and their products appear to be well received so far. Marketing is always the lynch pin imo. You get it wrong and your done, you get it right and you still may be done, but you hit a home run and that is when the magic happens my friend.
A rational valuation would require an earnings per share (EPS) of $.25 at a multiple of 20xEPS to get to $5/share. That would mean they'd have to turn a profit of about $67 million/year. That's about $5 or $6 million/month.
Will worldwide retail get us there with some combination of MCIG, VCIG and Vapolution - perhaps throwing in LiquCig. I think it's possible within a year or two. But then the market isn't always rational and will be looking ahead to profits in the next 6 to 12 months so it could happen sooner than we think.