An eternal quandary for art is that it must make money and yet also forget it. While makers can get very rich from their work, and should be able to do so, money should not be the first and last question on their lips.
It cheapens the product if the player is reminded of its cost. That in turn sours the experience, and is more likely to make players feel bad than good. When was the last time you played a slot machine that changed your life or even just made you really smile? I'm betting never.
A ticket to a show is the price you pay to get in the door, but once that sting is past, the art itself is generous and human. Generosity of spirit is how you connect with players. It's not charging per level, it's giving away 150 of them. It's not exacting forced tolls from players through freemium purchases, it's giving a whole lot of game away for free and charging in a clear fashion with no deception.
The goal of art is to connect with an audience, not to create a business model. That is as true for games as for anything else. You are in the thauma industry, to make magic not money. The money should just be the happy upside.
While investors may think otherwise, a game which is just a dressed up money engine usually does not connect with a major audience. They sense the scam and expect you to screw them. Gambling plays into this by offering tantalising rewards to players willing to be screwed, but for most games this is the wrong road to take.
Such companies end up having to rely on well-known games (like Bingo) or small subsets of users who won't scale (like penny auctions), or extremely opportunistic distribution (like Zynga). All of these avenues are crowded with competitors hawking similar products, and the law of the jungle is in full force. Your Bingo or your pony dress up game on Facebook looks like everyone else's and feels just as cheap.
Your best option is probably to go the other way. Build a fan base by being generous in spirit. Give, keep giving, and treat the money as a gift back from the audience rather than a toll. Worry about how your players feel rather than the bottom line, and the bottom line will sort itself out.
Many of the biggest games in the world are also the most generous, and that is why they endure. Communities are based on spirit rather than economics, and they are the secret to your success.