The single thing that can make trading into gambling, or gambling into a business like trading is:
A TESTED SYSTEM.
Trading is gambling when the trader has no system ("discretionary" trading). Because you are taking risk without knowing whether you are more likely to succeed or to fail.
Conversely, Gambling is a good, reliable business when you have a system that reliably predicts that you have a better chance of success than not. If you know you are likely to succeed, Gambling is a perfectly good business. Ask any casino owner.
Therfore, starting a business without information indicating that success is more likely than not (=a tested system), is also Gambling. For example, if you open a restaurant or a retail shop, but fail to do cashflow projections, a business plan, survey potential customers and the like, you are Gambling.
So the difference between any business and Gambling is having a system, or a plan, that has been tested and shown that it is likely to succeed.
This thread reminds me of discussions regarding how to differentiate a hobby from a business. (Ans: profit)