Your advice is good, but, despite what a lot of sources say, the quote doesn't come from Aristotle. It originated in F. Scott Fitzgerald's The Crack-Up: "the test of a first-rate intelligence is the ability to hold two opposed ideas in the mind at the same time, and still retain the ability to function."
Aristotle says that a good intellect will not require more or less rigor than a topic allows. Nichomachean Ethics I 1 1094b23: "The mark of the educated man is to seek precision insofar as each class allows it, so far as the nature of the subject-matter admits. To accept probable argumentation from a mathematician is like asking a rhetorician for formal proof." I.e. the two are equally absurd.
Philosophers other than Rand observe what they call the principle of charity: when in doubt about how to read a text, prefer the interpretation that makes it come out correct.
Why can't you do both? Software can't be taking up all of your time. Why not do other things after you're finished with the regular job? Why not keep your full time job, and do the other interests part time, at least for now?
You may find out you're not really all that interested in writing symphonies with the majority of your time. You may find out a solid stream of income is worth more to you than you'd thought. Setting company goals is someone's full time job somewhere, and you might discover you don't really like having that responsibility, even while still appreciating the goals/purpose being set.
You'll wind up discovering loads of facets to your other interests you didn't even know existed, along with how you like those facets, and the interests will inevitably become different things to you entirely than how you think about them now - maybe better, maybe worse. Fidgeting with those interests part time can show you those facets without you needing to devote time (and possible heartache) to worrying about a livelihood.
In my opinion, a life "plunge" is only good when you have some realistic idea of a good outcome, whatever that means to you. But, that's from a guy who has never done a plunge and never intends to. I like the try-before-you-buy method. But definitely try. What's the point of living if you don't do the living? If you think a plunge is for you, do it. There's truth to "if it don't kill you..."
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Audio recordings of Ayn Rand's Ford Hall Lectures, nearly all, are available for free listening at the ARI website: https://ari.aynrand.org/issues/government-and-business/more#filter-bar