if you suspect you aren't the most sophisticated gambler, then maybe it doesn't pay? Honestly, sports betting is orders of magnitude less sophisticated than Wall Street, so you have a better chance of finding an edge that others haven't also found.
Also, it's easy to imagine that there are a lot of "unskilled" betters, i.e. old folks betting for the thrill of it, people betting a few bucks just for kicks, ... With wall street, there might be a few unskilled people, but they are probably a small minority.
They're both the exact same thing when it comes to exchanges. I was working for a betting exchange and a market maker for a while, taking 500 orders a second and arbitraging between different competitors, before moving back to finance. It's quite interesting actually.
A lot of the market is not tradable though. On one end of the market, gambling is often a state monopoly with high spread and high margins (if not prohibited entirely), while on the other end there are large trades going on in private or closed circles.
