The reality they don't let you in on is that though we can be everything we want to be, the problem is that we can't be everything at the same time. In the end you will always be pro at max of one or two things. And as per meaning of pro, it is when you are as good as those making a full-time living of it.
I try to advice people who want to add this and that to their skills to be more focused. You can and should read wide, but, when it comes to building a career, stick to one field. Don't dabble into other fields except it's to support your primary field.
My primary field is data analysis. All my adventure into the world of finance and programming is to support that primary field. Finance because most of my high paying projects are in the finance field. And programming because it gives me a great edge and it's the only way to build a product/service I can mass sell. The one thing you won't find me do is take a certification exam in finance or programming. Or try to switch completely to one of those fields.
Yet, the few times I have had to dabble into other fields to complete a client project I encounter the problem of battling too many issues. The same way I see people battle issues in Excel that I can fix in seconds. And what's worse about them is that once you switch again, all the knowledge gained begins to wither and by time you have a similar project it is almost the same amount of work and issues to tackle. But with your core field, you glide. Soar is more like it. You get more done and keep building on existing expertise.