The stock market makes a great investment because it offers something for everyone. If you want to invest into something for the long term then studies have shows the market appreciates faster than pretty much every other asset class out there including bonds, real estate, and so on over the long term (20+ years). Provided you pick strong companies.
Another advantage is that it offers a lot of options. There are a lot of different strategies and methods for making money in the stock market and most I talk about on this site.
Finally there is a lot of potential. There really is no limit to how much or how fast you can make money from the market. That is why, every once in a while you hear stories from people like Nicolas Darvas who managed to turn $10,000 into $2,000,000 in 18 months. It is not common, but it shows just how much potential there really is in the market.
I realize that not everyone wants to invest in the stock market. But investing into something whether it be bonds, commodities, or real estate can have a major impact on your financial future and is well worth looking into.