So far as I can see, (but can't speak from experience, alas!), the best ways of getting enough dough to be able to live outside the system, is to use part of the system.
Like an artist or writer getting royalties, or making/inventing something that needs a licence to use, so you get paid every time it is used, without involving your own time and effort once the initial work is done.
But even as a successful writer you will have the frantic publisher sitting on you for the next book that will make him rich, so your time will not be entirely your own. And as said above, if you successfully invent something, unless you are uniquely placed to control its raw materials and production, somebody will soon take your idea and manufacture something similar but cheaper, or have it made somewhere cheaper, if it is going to be profitable.
There are very few trades or professions where you can make big money on a hourly rate, and some of those that pay well we might not want to do for ethical reasons. Hourly-paid work, as we all well know, ties you in pretty closely to the system: even if the hours are well-paid, they are usually at somebody else's convenience, not ours.
Money invested is not always money wisely invested. I personally know people who lost tens of thousands in private pensions with supposedly reputable companies in the financial crash of 2008. Twenty or thirty years of payments utterly lost. Devastating.