Here's a funny truth about jobs: As much as we tell graduating college seniors and new job-market entries to build their resumes with a nice, clear, linear story, sometimes you're actually much better at the job you end up doing because you've been doing something else for much longer. There are plenty of examples: Steve Jobs's affinity for calligraphy made him think about fonts and design differently. Hakeem Olajuwon and Jason Kidd were both soccer players before they made it big in basketball. Elite athletes like Roger Staubach and Magic Johnson later became CEOs.

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But even if we're to accept that experience as a community activist might make you a better business leader — or time spent as an actor or a doctor might prepare you for politics — we tend to be blind to these examples in our own lives. Just last year, I saw something like this hitting close to home: I learned a good friend had been repeatedly buying and then re-selling used clothes on eBay -- a habit curated over a decade. She'd purchase a dress for $80, wear it for a month or two and then sell it for $200. When she did it for fun, it was just so she could "pay Wal-Mart prices for Neiman Marcus clothes." But then she started doing it deliberately: buying at or under value and selling for more -- and she made margins between 15 and 200 percent, every time.

This struck me for two reasons:

First: Her confidence and intuitive sense of what products are worth. She was seeing a picture of cost and value that others missed — and profiting time after time.

Second: It seemed pretty damn familiar. In fact it reminded me of the skill set used by Wall Street proprietary ("prop") traders and investors — the people who power a large segment of the global economy, only they're fiddling with a lot more zeroes.

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Every day, Wall Street traders do roughly the same thing as my friend: They buy undervalued things and sell them later for higher prices. Only instead of designer bags and shoes, they buy and sell Apple stock, oil, gold or silver and other commodities. And they get paid $5 million, $10 million, even $1 billion a year.

But the underlying skills (save the cheats) are close.

The idea of transferable skills sometimes sounds too good, too optimistic, too outlandish. But I disagree — and so did my friend Edie Hunt, a longtime partner at Goldman Sachs and a former trader, who for years oversaw most of the hiring of traders at the firm. When I floated the idea past her, she said I was completely correct. In fact, she added, she'd spent years trying to point out this very notion to potential new hires, many of whom were women with a knack for at-home trading, assessing value and making smart cash.

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This isn't to say that trading is easy — it's not. And it's not considered a midlife career switch for a reason: It takes time to develop cunning, and thick skin to withstand the constant barrage of accountability that comes on trading floors. But if you've been building those muscles of judgment, of valuation, of cost cunning, for some time — and you've got the hunger to think big — this could be game-changing for your future.

Add to that the reality and old wisdom that women day-trade more (and better) than men — and it's a groundbreaking idea. Especially for trading — still a male-dominated corner of the historically testosterone-fueled Wall Street — where women make up no more than 5 percent of employees.

Edie said the idea didn't always carry, but when women were reluctant to step into the jungle on the trading floor, she'd insist they shouldn't pass on trading altogether — indeed, she'd urge them to "put down eBay and opt for e-Trade."

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Turns out a number of studies back up my hypothesis — and reinforce Edie's position. Online day-trading has huge potential as a cash cow, but studies in the 1990s out of Yale's economics department suggest that many people who do it aren't successful. Except those who already have a record of success. Which is to say that plenty of people who are day-trading all day aren't very good at it, but if you are good at it, there are huge potential margins of return. And eBay might be a brilliant place to get good at it — or at least to find out if you've got the knack.

It's not clear if any of the big banks have picked up on this phenomenon — other than a few folks on the inside, like Edie, who've noticed the correlation. But they should: not least because one of the fastest-growing retailers in the country, fashion store Nasty Gal, started that way; and, as my enterprising friend points out, there are thousands of Nasty Gals out there. Which means eBay could be a rich talent pool for recruiters -- or any smart entrepreneur -- to consider hiring from or looking to for inspiration. And even more importantly: These high-performing eBay traders may not recognize the mad skills they've got — and how valuable they could be if taken to a far more lucrative venue.

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Which is funny because trading — at home on eBay or on the floor of a stock exchange — is an exercise in creative entrepreneurship. Or to put it differently: It's all about confidence, about seeing what other people don't dare to. It's not unlike the culture of eBay when it first started. And for anyone who doesn't believe me, they should believe the CEO of eBay, John Donahoe. I talked to him about this very idea at a dinner party, and he, too, confirmed what I'd been guessing at — that eBay traders are doing real work, making real money and building skills that play outside the game they might know best.

People will often say no to you before they say yes. Joe Montana was dismissed as a baseball player before becoming America's great quarterback. Not to mention a former Chicago-community activist and freshman senator — whom plenty doubted before his meteoric rise. But here's the exciting takeaway from the story of my eBay-savvy friends: You just might be sitting on a gold mine, literally and figuratively, if you've got the confidence to, well, take your skills and trade up.