OK, someone has already mentioned trading so lets start with that.
Forex, do some people make money, yes. Are there shit loads of youtube channels and websites selling forex knowledge, yes. What does that tell you?
It means that most people can’t make money from actually doing it, they only make money from talking about doing it. Its also a zero sum game. You are also against large banks who hire phd’s to write algorithms and spend massive sums to deal with latency issues to move both in and out of a trade whilst you are still working out which pair to trade.
Day trading on the stockmarket. Well at least this is not a zero sum game but everything else about forex still applies.
CFD’s and options, if you don’t know what they are then theses aren’t for you, if you do they you already know if they suit you or not.
Longer term trading on the stockmarket, IOW investing. Consider Growth at a Reasonable Price and its derivatives, High yield and Value. A good number of people do this and are successful with trackable records. But guess what, its not sexy and doesn’t have the appeal of “trading” so people don’t try and sell it. OTOH it does work.
So, how do you learn about it, go to places like zero alpha and be prepared to read a great deal to sort the wheat from the chaff.
Pro tip, ignore Buffett, not because he started as an asset stripper and hedgie but because he is a shit teacher.
No idea how subs will help with this as most people would find the required reading to be tediously boring in the extreme (also I don’t know how the subs work as that’s a trade secret).
About business, get good at sales or hire someone who is, then to a great extent it doesn’t really matter what you do. For example Ive recently set up a business to do building work/renovations, we plan to be better at sales than the smaller contractors and when we win contracts we will sub the work out to small contractors and then get big enough to start doing our own projects. Will this work, no idea but at least we are taking action to find out.
Subs will help with this by enhancing alpha characteristics and sales skill.