Even though it IS about the money, it shouldn't just be about the money. Your job is something you spend a lot of time doing so you better be interested in whatever it is.
Heres my advice from the money side of it. The more technical education required for the product, the better the position. Having said that, you can sell new cars and earn an excellent income without ever buying a new car. The hours are tough and you have to be good at sales. And you ust believe in yourself. Of course, you want to represent quality products and services too.
Two words, Real estate (or is that one word, lol). People always need a home, so its always active. Yes there were bad years like during the GFC in 2008, but it recovered fast and tens of millions of homes would have been sold between now and then.
I think selling methods, courses and guides are great today. I see some people, especially on YouTube, who are making a killing selling their selling methods online. It sounds weird. YouTube is great for marketing because it is personable. Many youtubers first brand themselves, then they market in a clever way a series of products (either their own or someone elses as an affiliate) for a nice price.