Image source: Getty Images.

Wouldn't it be great to find the next big thing? Just to name a couple of past examples, getting into when it was just an online bookstore, or into Apple before the iPod brought the company back to relevance in the tech industry, would have turned investments of just a few thousand dollars into million-dollar nest eggs. And while it's impossible to know with any degree of certainty what companies will become the Amazons and Apples of tomorrow, here are three young contenders full of potential.

The future of payment processing

Square (NYSE:SQ), the up-and-coming payment processing company, has yet to post a profit. And it's not forecast to produce positive earnings this year or next.

However, if you're looking at the bottom-line numbers with Square, you're missing the point. The opportunity here is staggering. The U.S. payments market is about $10 trillion per year in size, and even after increasing its revenue by 524% from 2012 to 2015, Square has only about 0.5% of the market at this point.

Image source: Square investor presentation.

Square's low-priced hardware, simple cost structure, and innovative payment processing solutions could be a game changer. In addition to the huge addressable market I already mentioned, this could help Square target the 20 million U.S. businesses that still don't accept credit cards.

Analysts forecast that square will finally begin to turn a profit in 2018, but it's more important for long-term investors for Square to continue to grow and innovate. It's anybody's guess how big and (eventually) profitable Square will be, but one thing is for sure -- the potential is there.

Banking without the overhead

BofI Holding, Inc. (NYSE:AX) operates BofI Federal Bank (short for "Bank of Internet"), an online bank with $7.6 billion in assets and 15 years in business.

The advantage of BofI is that because it's an internet bank, operating out of a single physical office in San Diego, the bank doesn't have to worry about the cost of building, equipping, and staffing branches. As a result, the company has some of the lowest expenses in the industry and some of the best profitability metrics. For example, the average bank produces a 6.69% return on equity and a 0.75% return on average assets right now. BofI generates 22.62% and 1.89%, respectively, in the 95th and 92nd percentile of the banking industry.

As far as the "could make you rich" part is concerned, the growth potential here is simply enormous. Over the past year alone, BofI's deposits have grown by 36%, and the bank's diluted EPS has grown at an annualized rate of 34% over the past four years. Even more remarkable is that it was able to grow like this without sacrificing quality - BofI has one of the lowest charge-off rates in the business.

Image source: BofI investor presentation.

Now could be a great time to buy BofI. Thanks to some largely unfounded accusations and a high volume of short-selling, the bank trades for 39% less than it did last October before the allegations surfaced, and for just 11.9 times TTM earnings, a remarkably low P/E multiple considering its growth rate.

P2P lending could get back on track

To me, Lending Club (NYSE:LC) is one of the most disappointing IPO stocks of the past few years. Peer-to-peer (P2P) lending was being hyped as the next big thing in the financial industry, but shares have shed 73% since the first trading day in late 2014. The biggest reason for the drop was a lending scandal that resulted in the CEO's departure, but questions of the business model's long-term sustainability add another element of uncertainty. Plus, during the second quarter of 2016, Lending Club saw its origination volume drop for the first time ever.

Image source: Lending Club investor presentation.

Even so, if Lending Club does manage to win back investor confidence and turn its business around, it could potentially be extremely successful, especially if it gets its growth trajectory back on track. Lending Club's operating expenses of 2% to 3% of outstanding loan balances are far less than those of traditional lenders, and the company can offer better returns to its "lenders" than investing in pretty much any other type of fixed-income security. And it can offer borrowers lower rates on unsecured personal loans than banks can.

To sum it up, P2P lending definitely has potential. The question is, will Lending Club turn things around and capitalize on that potential? If it can, investors who got in at the current depressed share price stand to make a lot of money.

Approach these with caution

Notice that I said these stocks could make you rich, not that they will. These companies could eventually become the next Visa or U.S. Bancorp, but they could also end up going broke just as easily. My point is this: If you want a safe bet, a portfolio of well-established blue-chip stocks has your name written all over it. On the other hand, if you have some extra cash you'd like to take a chance with, the risk/reward profiles of these three companies are pretty appealing.

This article represents the opinion of the writer, who may disagree with the “official” recommendation position of a Motley Fool premium advisory service. We’re motley! Questioning an investing thesis -- even one of our own -- helps us all think critically about investing and make decisions that help us become smarter, happier, and richer.